shmem.c revision 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2
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) 2002-2004 Hugh Dickins. 10 * Copyright (C) 2002-2004 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 <linux/xattr.h> 49#include <asm/uaccess.h> 50#include <asm/div64.h> 51#include <asm/pgtable.h> 52 53/* This magic number is used in glibc for posix shared memory */ 54#define TMPFS_MAGIC 0x01021994 55 56#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) 57#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) 58#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) 59 60#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) 61#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT) 62 63#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) 64 65/* info->flags needs VM_flags to handle pagein/truncate races efficiently */ 66#define SHMEM_PAGEIN VM_READ 67#define SHMEM_TRUNCATE VM_WRITE 68 69/* Definition to limit shmem_truncate's steps between cond_rescheds */ 70#define LATENCY_LIMIT 64 71 72/* Pretend that each entry is of this size in directory's i_size */ 73#define BOGO_DIRENT_SIZE 20 74 75/* Keep swapped page count in private field of indirect struct page */ 76#define nr_swapped private 77 78/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ 79enum sgp_type { 80 SGP_QUICK, /* don't try more than file page cache lookup */ 81 SGP_READ, /* don't exceed i_size, don't allocate page */ 82 SGP_CACHE, /* don't exceed i_size, may allocate page */ 83 SGP_WRITE, /* may exceed i_size, may allocate page */ 84}; 85 86static int shmem_getpage(struct inode *inode, unsigned long idx, 87 struct page **pagep, enum sgp_type sgp, int *type); 88 89static inline struct page *shmem_dir_alloc(unsigned int gfp_mask) 90{ 91 /* 92 * The above definition of ENTRIES_PER_PAGE, and the use of 93 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 94 * might be reconsidered if it ever diverges from PAGE_SIZE. 95 */ 96 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT); 97} 98 99static inline void shmem_dir_free(struct page *page) 100{ 101 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 102} 103 104static struct page **shmem_dir_map(struct page *page) 105{ 106 return (struct page **)kmap_atomic(page, KM_USER0); 107} 108 109static inline void shmem_dir_unmap(struct page **dir) 110{ 111 kunmap_atomic(dir, KM_USER0); 112} 113 114static swp_entry_t *shmem_swp_map(struct page *page) 115{ 116 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 117} 118 119static inline void shmem_swp_balance_unmap(void) 120{ 121 /* 122 * When passing a pointer to an i_direct entry, to code which 123 * also handles indirect entries and so will shmem_swp_unmap, 124 * we must arrange for the preempt count to remain in balance. 125 * What kmap_atomic of a lowmem page does depends on config 126 * and architecture, so pretend to kmap_atomic some lowmem page. 127 */ 128 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 129} 130 131static inline void shmem_swp_unmap(swp_entry_t *entry) 132{ 133 kunmap_atomic(entry, KM_USER1); 134} 135 136static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 137{ 138 return sb->s_fs_info; 139} 140 141/* 142 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 143 * for shared memory and for shared anonymous (/dev/zero) mappings 144 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 145 * consistent with the pre-accounting of private mappings ... 146 */ 147static inline int shmem_acct_size(unsigned long flags, loff_t size) 148{ 149 return (flags & VM_ACCOUNT)? 150 security_vm_enough_memory(VM_ACCT(size)): 0; 151} 152 153static inline void shmem_unacct_size(unsigned long flags, loff_t size) 154{ 155 if (flags & VM_ACCOUNT) 156 vm_unacct_memory(VM_ACCT(size)); 157} 158 159/* 160 * ... whereas tmpfs objects are accounted incrementally as 161 * pages are allocated, in order to allow huge sparse files. 162 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 163 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 164 */ 165static inline int shmem_acct_block(unsigned long flags) 166{ 167 return (flags & VM_ACCOUNT)? 168 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE)); 169} 170 171static inline void shmem_unacct_blocks(unsigned long flags, long pages) 172{ 173 if (!(flags & VM_ACCOUNT)) 174 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 175} 176 177static struct super_operations shmem_ops; 178static struct address_space_operations shmem_aops; 179static struct file_operations shmem_file_operations; 180static struct inode_operations shmem_inode_operations; 181static struct inode_operations shmem_dir_inode_operations; 182static struct inode_operations shmem_special_inode_operations; 183static struct vm_operations_struct shmem_vm_ops; 184 185static struct backing_dev_info shmem_backing_dev_info = { 186 .ra_pages = 0, /* No readahead */ 187 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, 188 .unplug_io_fn = default_unplug_io_fn, 189}; 190 191static LIST_HEAD(shmem_swaplist); 192static DEFINE_SPINLOCK(shmem_swaplist_lock); 193 194static void shmem_free_blocks(struct inode *inode, long pages) 195{ 196 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 197 if (sbinfo) { 198 spin_lock(&sbinfo->stat_lock); 199 sbinfo->free_blocks += pages; 200 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 201 spin_unlock(&sbinfo->stat_lock); 202 } 203} 204 205/* 206 * shmem_recalc_inode - recalculate the size of an inode 207 * 208 * @inode: inode to recalc 209 * 210 * We have to calculate the free blocks since the mm can drop 211 * undirtied hole pages behind our back. 212 * 213 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 214 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 215 * 216 * It has to be called with the spinlock held. 217 */ 218static void shmem_recalc_inode(struct inode *inode) 219{ 220 struct shmem_inode_info *info = SHMEM_I(inode); 221 long freed; 222 223 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 224 if (freed > 0) { 225 info->alloced -= freed; 226 shmem_unacct_blocks(info->flags, freed); 227 shmem_free_blocks(inode, freed); 228 } 229} 230 231/* 232 * shmem_swp_entry - find the swap vector position in the info structure 233 * 234 * @info: info structure for the inode 235 * @index: index of the page to find 236 * @page: optional page to add to the structure. Has to be preset to 237 * all zeros 238 * 239 * If there is no space allocated yet it will return NULL when 240 * page is NULL, else it will use the page for the needed block, 241 * setting it to NULL on return to indicate that it has been used. 242 * 243 * The swap vector is organized the following way: 244 * 245 * There are SHMEM_NR_DIRECT entries directly stored in the 246 * shmem_inode_info structure. So small files do not need an addional 247 * allocation. 248 * 249 * For pages with index > SHMEM_NR_DIRECT there is the pointer 250 * i_indirect which points to a page which holds in the first half 251 * doubly indirect blocks, in the second half triple indirect blocks: 252 * 253 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 254 * following layout (for SHMEM_NR_DIRECT == 16): 255 * 256 * i_indirect -> dir --> 16-19 257 * | +-> 20-23 258 * | 259 * +-->dir2 --> 24-27 260 * | +-> 28-31 261 * | +-> 32-35 262 * | +-> 36-39 263 * | 264 * +-->dir3 --> 40-43 265 * +-> 44-47 266 * +-> 48-51 267 * +-> 52-55 268 */ 269static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 270{ 271 unsigned long offset; 272 struct page **dir; 273 struct page *subdir; 274 275 if (index < SHMEM_NR_DIRECT) { 276 shmem_swp_balance_unmap(); 277 return info->i_direct+index; 278 } 279 if (!info->i_indirect) { 280 if (page) { 281 info->i_indirect = *page; 282 *page = NULL; 283 } 284 return NULL; /* need another page */ 285 } 286 287 index -= SHMEM_NR_DIRECT; 288 offset = index % ENTRIES_PER_PAGE; 289 index /= ENTRIES_PER_PAGE; 290 dir = shmem_dir_map(info->i_indirect); 291 292 if (index >= ENTRIES_PER_PAGE/2) { 293 index -= ENTRIES_PER_PAGE/2; 294 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 295 index %= ENTRIES_PER_PAGE; 296 subdir = *dir; 297 if (!subdir) { 298 if (page) { 299 *dir = *page; 300 *page = NULL; 301 } 302 shmem_dir_unmap(dir); 303 return NULL; /* need another page */ 304 } 305 shmem_dir_unmap(dir); 306 dir = shmem_dir_map(subdir); 307 } 308 309 dir += index; 310 subdir = *dir; 311 if (!subdir) { 312 if (!page || !(subdir = *page)) { 313 shmem_dir_unmap(dir); 314 return NULL; /* need a page */ 315 } 316 *dir = subdir; 317 *page = NULL; 318 } 319 shmem_dir_unmap(dir); 320 return shmem_swp_map(subdir) + offset; 321} 322 323static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 324{ 325 long incdec = value? 1: -1; 326 327 entry->val = value; 328 info->swapped += incdec; 329 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) 330 kmap_atomic_to_page(entry)->nr_swapped += incdec; 331} 332 333/* 334 * shmem_swp_alloc - get the position of the swap entry for the page. 335 * If it does not exist allocate the entry. 336 * 337 * @info: info structure for the inode 338 * @index: index of the page to find 339 * @sgp: check and recheck i_size? skip allocation? 340 */ 341static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 342{ 343 struct inode *inode = &info->vfs_inode; 344 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 345 struct page *page = NULL; 346 swp_entry_t *entry; 347 348 if (sgp != SGP_WRITE && 349 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 350 return ERR_PTR(-EINVAL); 351 352 while (!(entry = shmem_swp_entry(info, index, &page))) { 353 if (sgp == SGP_READ) 354 return shmem_swp_map(ZERO_PAGE(0)); 355 /* 356 * Test free_blocks against 1 not 0, since we have 1 data 357 * page (and perhaps indirect index pages) yet to allocate: 358 * a waste to allocate index if we cannot allocate data. 359 */ 360 if (sbinfo) { 361 spin_lock(&sbinfo->stat_lock); 362 if (sbinfo->free_blocks <= 1) { 363 spin_unlock(&sbinfo->stat_lock); 364 return ERR_PTR(-ENOSPC); 365 } 366 sbinfo->free_blocks--; 367 inode->i_blocks += BLOCKS_PER_PAGE; 368 spin_unlock(&sbinfo->stat_lock); 369 } 370 371 spin_unlock(&info->lock); 372 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO); 373 if (page) { 374 page->nr_swapped = 0; 375 } 376 spin_lock(&info->lock); 377 378 if (!page) { 379 shmem_free_blocks(inode, 1); 380 return ERR_PTR(-ENOMEM); 381 } 382 if (sgp != SGP_WRITE && 383 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 384 entry = ERR_PTR(-EINVAL); 385 break; 386 } 387 if (info->next_index <= index) 388 info->next_index = index + 1; 389 } 390 if (page) { 391 /* another task gave its page, or truncated the file */ 392 shmem_free_blocks(inode, 1); 393 shmem_dir_free(page); 394 } 395 if (info->next_index <= index && !IS_ERR(entry)) 396 info->next_index = index + 1; 397 return entry; 398} 399 400/* 401 * shmem_free_swp - free some swap entries in a directory 402 * 403 * @dir: pointer to the directory 404 * @edir: pointer after last entry of the directory 405 */ 406static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir) 407{ 408 swp_entry_t *ptr; 409 int freed = 0; 410 411 for (ptr = dir; ptr < edir; ptr++) { 412 if (ptr->val) { 413 free_swap_and_cache(*ptr); 414 *ptr = (swp_entry_t){0}; 415 freed++; 416 } 417 } 418 return freed; 419} 420 421static int shmem_map_and_free_swp(struct page *subdir, 422 int offset, int limit, struct page ***dir) 423{ 424 swp_entry_t *ptr; 425 int freed = 0; 426 427 ptr = shmem_swp_map(subdir); 428 for (; offset < limit; offset += LATENCY_LIMIT) { 429 int size = limit - offset; 430 if (size > LATENCY_LIMIT) 431 size = LATENCY_LIMIT; 432 freed += shmem_free_swp(ptr+offset, ptr+offset+size); 433 if (need_resched()) { 434 shmem_swp_unmap(ptr); 435 if (*dir) { 436 shmem_dir_unmap(*dir); 437 *dir = NULL; 438 } 439 cond_resched(); 440 ptr = shmem_swp_map(subdir); 441 } 442 } 443 shmem_swp_unmap(ptr); 444 return freed; 445} 446 447static void shmem_free_pages(struct list_head *next) 448{ 449 struct page *page; 450 int freed = 0; 451 452 do { 453 page = container_of(next, struct page, lru); 454 next = next->next; 455 shmem_dir_free(page); 456 freed++; 457 if (freed >= LATENCY_LIMIT) { 458 cond_resched(); 459 freed = 0; 460 } 461 } while (next); 462} 463 464static void shmem_truncate(struct inode *inode) 465{ 466 struct shmem_inode_info *info = SHMEM_I(inode); 467 unsigned long idx; 468 unsigned long size; 469 unsigned long limit; 470 unsigned long stage; 471 unsigned long diroff; 472 struct page **dir; 473 struct page *topdir; 474 struct page *middir; 475 struct page *subdir; 476 swp_entry_t *ptr; 477 LIST_HEAD(pages_to_free); 478 long nr_pages_to_free = 0; 479 long nr_swaps_freed = 0; 480 int offset; 481 int freed; 482 483 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 484 idx = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 485 if (idx >= info->next_index) 486 return; 487 488 spin_lock(&info->lock); 489 info->flags |= SHMEM_TRUNCATE; 490 limit = info->next_index; 491 info->next_index = idx; 492 topdir = info->i_indirect; 493 if (topdir && idx <= SHMEM_NR_DIRECT) { 494 info->i_indirect = NULL; 495 nr_pages_to_free++; 496 list_add(&topdir->lru, &pages_to_free); 497 } 498 spin_unlock(&info->lock); 499 500 if (info->swapped && idx < SHMEM_NR_DIRECT) { 501 ptr = info->i_direct; 502 size = limit; 503 if (size > SHMEM_NR_DIRECT) 504 size = SHMEM_NR_DIRECT; 505 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size); 506 } 507 if (!topdir) 508 goto done2; 509 510 BUG_ON(limit <= SHMEM_NR_DIRECT); 511 limit -= SHMEM_NR_DIRECT; 512 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 513 offset = idx % ENTRIES_PER_PAGE; 514 idx -= offset; 515 516 dir = shmem_dir_map(topdir); 517 stage = ENTRIES_PER_PAGEPAGE/2; 518 if (idx < ENTRIES_PER_PAGEPAGE/2) { 519 middir = topdir; 520 diroff = idx/ENTRIES_PER_PAGE; 521 } else { 522 dir += ENTRIES_PER_PAGE/2; 523 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 524 while (stage <= idx) 525 stage += ENTRIES_PER_PAGEPAGE; 526 middir = *dir; 527 if (*dir) { 528 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 529 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 530 if (!diroff && !offset) { 531 *dir = NULL; 532 nr_pages_to_free++; 533 list_add(&middir->lru, &pages_to_free); 534 } 535 shmem_dir_unmap(dir); 536 dir = shmem_dir_map(middir); 537 } else { 538 diroff = 0; 539 offset = 0; 540 idx = stage; 541 } 542 } 543 544 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 545 if (unlikely(idx == stage)) { 546 shmem_dir_unmap(dir); 547 dir = shmem_dir_map(topdir) + 548 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 549 while (!*dir) { 550 dir++; 551 idx += ENTRIES_PER_PAGEPAGE; 552 if (idx >= limit) 553 goto done1; 554 } 555 stage = idx + ENTRIES_PER_PAGEPAGE; 556 middir = *dir; 557 *dir = NULL; 558 nr_pages_to_free++; 559 list_add(&middir->lru, &pages_to_free); 560 shmem_dir_unmap(dir); 561 cond_resched(); 562 dir = shmem_dir_map(middir); 563 diroff = 0; 564 } 565 subdir = dir[diroff]; 566 if (subdir && subdir->nr_swapped) { 567 size = limit - idx; 568 if (size > ENTRIES_PER_PAGE) 569 size = ENTRIES_PER_PAGE; 570 freed = shmem_map_and_free_swp(subdir, 571 offset, size, &dir); 572 if (!dir) 573 dir = shmem_dir_map(middir); 574 nr_swaps_freed += freed; 575 if (offset) 576 spin_lock(&info->lock); 577 subdir->nr_swapped -= freed; 578 if (offset) 579 spin_unlock(&info->lock); 580 BUG_ON(subdir->nr_swapped > offset); 581 } 582 if (offset) 583 offset = 0; 584 else if (subdir) { 585 dir[diroff] = NULL; 586 nr_pages_to_free++; 587 list_add(&subdir->lru, &pages_to_free); 588 } 589 } 590done1: 591 shmem_dir_unmap(dir); 592done2: 593 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 594 /* 595 * Call truncate_inode_pages again: racing shmem_unuse_inode 596 * may have swizzled a page in from swap since vmtruncate or 597 * generic_delete_inode did it, before we lowered next_index. 598 * Also, though shmem_getpage checks i_size before adding to 599 * cache, no recheck after: so fix the narrow window there too. 600 */ 601 truncate_inode_pages(inode->i_mapping, inode->i_size); 602 } 603 604 spin_lock(&info->lock); 605 info->flags &= ~SHMEM_TRUNCATE; 606 info->swapped -= nr_swaps_freed; 607 if (nr_pages_to_free) 608 shmem_free_blocks(inode, nr_pages_to_free); 609 shmem_recalc_inode(inode); 610 spin_unlock(&info->lock); 611 612 /* 613 * Empty swap vector directory pages to be freed? 614 */ 615 if (!list_empty(&pages_to_free)) { 616 pages_to_free.prev->next = NULL; 617 shmem_free_pages(pages_to_free.next); 618 } 619} 620 621static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 622{ 623 struct inode *inode = dentry->d_inode; 624 struct page *page = NULL; 625 int error; 626 627 if (attr->ia_valid & ATTR_SIZE) { 628 if (attr->ia_size < inode->i_size) { 629 /* 630 * If truncating down to a partial page, then 631 * if that page is already allocated, hold it 632 * in memory until the truncation is over, so 633 * truncate_partial_page cannnot miss it were 634 * it assigned to swap. 635 */ 636 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { 637 (void) shmem_getpage(inode, 638 attr->ia_size>>PAGE_CACHE_SHIFT, 639 &page, SGP_READ, NULL); 640 } 641 /* 642 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 643 * detect if any pages might have been added to cache 644 * after truncate_inode_pages. But we needn't bother 645 * if it's being fully truncated to zero-length: the 646 * nrpages check is efficient enough in that case. 647 */ 648 if (attr->ia_size) { 649 struct shmem_inode_info *info = SHMEM_I(inode); 650 spin_lock(&info->lock); 651 info->flags &= ~SHMEM_PAGEIN; 652 spin_unlock(&info->lock); 653 } 654 } 655 } 656 657 error = inode_change_ok(inode, attr); 658 if (!error) 659 error = inode_setattr(inode, attr); 660 if (page) 661 page_cache_release(page); 662 return error; 663} 664 665static void shmem_delete_inode(struct inode *inode) 666{ 667 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 668 struct shmem_inode_info *info = SHMEM_I(inode); 669 670 if (inode->i_op->truncate == shmem_truncate) { 671 shmem_unacct_size(info->flags, inode->i_size); 672 inode->i_size = 0; 673 shmem_truncate(inode); 674 if (!list_empty(&info->swaplist)) { 675 spin_lock(&shmem_swaplist_lock); 676 list_del_init(&info->swaplist); 677 spin_unlock(&shmem_swaplist_lock); 678 } 679 } 680 if (sbinfo) { 681 BUG_ON(inode->i_blocks); 682 spin_lock(&sbinfo->stat_lock); 683 sbinfo->free_inodes++; 684 spin_unlock(&sbinfo->stat_lock); 685 } 686 clear_inode(inode); 687} 688 689static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 690{ 691 swp_entry_t *ptr; 692 693 for (ptr = dir; ptr < edir; ptr++) { 694 if (ptr->val == entry.val) 695 return ptr - dir; 696 } 697 return -1; 698} 699 700static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 701{ 702 struct inode *inode; 703 unsigned long idx; 704 unsigned long size; 705 unsigned long limit; 706 unsigned long stage; 707 struct page **dir; 708 struct page *subdir; 709 swp_entry_t *ptr; 710 int offset; 711 712 idx = 0; 713 ptr = info->i_direct; 714 spin_lock(&info->lock); 715 limit = info->next_index; 716 size = limit; 717 if (size > SHMEM_NR_DIRECT) 718 size = SHMEM_NR_DIRECT; 719 offset = shmem_find_swp(entry, ptr, ptr+size); 720 if (offset >= 0) { 721 shmem_swp_balance_unmap(); 722 goto found; 723 } 724 if (!info->i_indirect) 725 goto lost2; 726 727 dir = shmem_dir_map(info->i_indirect); 728 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 729 730 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 731 if (unlikely(idx == stage)) { 732 shmem_dir_unmap(dir-1); 733 dir = shmem_dir_map(info->i_indirect) + 734 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 735 while (!*dir) { 736 dir++; 737 idx += ENTRIES_PER_PAGEPAGE; 738 if (idx >= limit) 739 goto lost1; 740 } 741 stage = idx + ENTRIES_PER_PAGEPAGE; 742 subdir = *dir; 743 shmem_dir_unmap(dir); 744 dir = shmem_dir_map(subdir); 745 } 746 subdir = *dir; 747 if (subdir && subdir->nr_swapped) { 748 ptr = shmem_swp_map(subdir); 749 size = limit - idx; 750 if (size > ENTRIES_PER_PAGE) 751 size = ENTRIES_PER_PAGE; 752 offset = shmem_find_swp(entry, ptr, ptr+size); 753 if (offset >= 0) { 754 shmem_dir_unmap(dir); 755 goto found; 756 } 757 shmem_swp_unmap(ptr); 758 } 759 } 760lost1: 761 shmem_dir_unmap(dir-1); 762lost2: 763 spin_unlock(&info->lock); 764 return 0; 765found: 766 idx += offset; 767 inode = &info->vfs_inode; 768 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) { 769 info->flags |= SHMEM_PAGEIN; 770 shmem_swp_set(info, ptr + offset, 0); 771 } 772 shmem_swp_unmap(ptr); 773 spin_unlock(&info->lock); 774 /* 775 * Decrement swap count even when the entry is left behind: 776 * try_to_unuse will skip over mms, then reincrement count. 777 */ 778 swap_free(entry); 779 return 1; 780} 781 782/* 783 * shmem_unuse() search for an eventually swapped out shmem page. 784 */ 785int shmem_unuse(swp_entry_t entry, struct page *page) 786{ 787 struct list_head *p, *next; 788 struct shmem_inode_info *info; 789 int found = 0; 790 791 spin_lock(&shmem_swaplist_lock); 792 list_for_each_safe(p, next, &shmem_swaplist) { 793 info = list_entry(p, struct shmem_inode_info, swaplist); 794 if (!info->swapped) 795 list_del_init(&info->swaplist); 796 else if (shmem_unuse_inode(info, entry, page)) { 797 /* move head to start search for next from here */ 798 list_move_tail(&shmem_swaplist, &info->swaplist); 799 found = 1; 800 break; 801 } 802 } 803 spin_unlock(&shmem_swaplist_lock); 804 return found; 805} 806 807/* 808 * Move the page from the page cache to the swap cache. 809 */ 810static int shmem_writepage(struct page *page, struct writeback_control *wbc) 811{ 812 struct shmem_inode_info *info; 813 swp_entry_t *entry, swap; 814 struct address_space *mapping; 815 unsigned long index; 816 struct inode *inode; 817 818 BUG_ON(!PageLocked(page)); 819 BUG_ON(page_mapped(page)); 820 821 mapping = page->mapping; 822 index = page->index; 823 inode = mapping->host; 824 info = SHMEM_I(inode); 825 if (info->flags & VM_LOCKED) 826 goto redirty; 827 swap = get_swap_page(); 828 if (!swap.val) 829 goto redirty; 830 831 spin_lock(&info->lock); 832 shmem_recalc_inode(inode); 833 if (index >= info->next_index) { 834 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 835 goto unlock; 836 } 837 entry = shmem_swp_entry(info, index, NULL); 838 BUG_ON(!entry); 839 BUG_ON(entry->val); 840 841 if (move_to_swap_cache(page, swap) == 0) { 842 shmem_swp_set(info, entry, swap.val); 843 shmem_swp_unmap(entry); 844 spin_unlock(&info->lock); 845 if (list_empty(&info->swaplist)) { 846 spin_lock(&shmem_swaplist_lock); 847 /* move instead of add in case we're racing */ 848 list_move_tail(&info->swaplist, &shmem_swaplist); 849 spin_unlock(&shmem_swaplist_lock); 850 } 851 unlock_page(page); 852 return 0; 853 } 854 855 shmem_swp_unmap(entry); 856unlock: 857 spin_unlock(&info->lock); 858 swap_free(swap); 859redirty: 860 set_page_dirty(page); 861 return WRITEPAGE_ACTIVATE; /* Return with the page locked */ 862} 863 864#ifdef CONFIG_NUMA 865static struct page *shmem_swapin_async(struct shared_policy *p, 866 swp_entry_t entry, unsigned long idx) 867{ 868 struct page *page; 869 struct vm_area_struct pvma; 870 871 /* Create a pseudo vma that just contains the policy */ 872 memset(&pvma, 0, sizeof(struct vm_area_struct)); 873 pvma.vm_end = PAGE_SIZE; 874 pvma.vm_pgoff = idx; 875 pvma.vm_policy = mpol_shared_policy_lookup(p, idx); 876 page = read_swap_cache_async(entry, &pvma, 0); 877 mpol_free(pvma.vm_policy); 878 return page; 879} 880 881struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry, 882 unsigned long idx) 883{ 884 struct shared_policy *p = &info->policy; 885 int i, num; 886 struct page *page; 887 unsigned long offset; 888 889 num = valid_swaphandles(entry, &offset); 890 for (i = 0; i < num; offset++, i++) { 891 page = shmem_swapin_async(p, 892 swp_entry(swp_type(entry), offset), idx); 893 if (!page) 894 break; 895 page_cache_release(page); 896 } 897 lru_add_drain(); /* Push any new pages onto the LRU now */ 898 return shmem_swapin_async(p, entry, idx); 899} 900 901static struct page * 902shmem_alloc_page(unsigned long gfp, struct shmem_inode_info *info, 903 unsigned long idx) 904{ 905 struct vm_area_struct pvma; 906 struct page *page; 907 908 memset(&pvma, 0, sizeof(struct vm_area_struct)); 909 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 910 pvma.vm_pgoff = idx; 911 pvma.vm_end = PAGE_SIZE; 912 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0); 913 mpol_free(pvma.vm_policy); 914 return page; 915} 916#else 917static inline struct page * 918shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx) 919{ 920 swapin_readahead(entry, 0, NULL); 921 return read_swap_cache_async(entry, NULL, 0); 922} 923 924static inline struct page * 925shmem_alloc_page(unsigned int __nocast gfp,struct shmem_inode_info *info, 926 unsigned long idx) 927{ 928 return alloc_page(gfp | __GFP_ZERO); 929} 930#endif 931 932/* 933 * shmem_getpage - either get the page from swap or allocate a new one 934 * 935 * If we allocate a new one we do not mark it dirty. That's up to the 936 * vm. If we swap it in we mark it dirty since we also free the swap 937 * entry since a page cannot live in both the swap and page cache 938 */ 939static int shmem_getpage(struct inode *inode, unsigned long idx, 940 struct page **pagep, enum sgp_type sgp, int *type) 941{ 942 struct address_space *mapping = inode->i_mapping; 943 struct shmem_inode_info *info = SHMEM_I(inode); 944 struct shmem_sb_info *sbinfo; 945 struct page *filepage = *pagep; 946 struct page *swappage; 947 swp_entry_t *entry; 948 swp_entry_t swap; 949 int error; 950 951 if (idx >= SHMEM_MAX_INDEX) 952 return -EFBIG; 953 /* 954 * Normally, filepage is NULL on entry, and either found 955 * uptodate immediately, or allocated and zeroed, or read 956 * in under swappage, which is then assigned to filepage. 957 * But shmem_prepare_write passes in a locked filepage, 958 * which may be found not uptodate by other callers too, 959 * and may need to be copied from the swappage read in. 960 */ 961repeat: 962 if (!filepage) 963 filepage = find_lock_page(mapping, idx); 964 if (filepage && PageUptodate(filepage)) 965 goto done; 966 error = 0; 967 if (sgp == SGP_QUICK) 968 goto failed; 969 970 spin_lock(&info->lock); 971 shmem_recalc_inode(inode); 972 entry = shmem_swp_alloc(info, idx, sgp); 973 if (IS_ERR(entry)) { 974 spin_unlock(&info->lock); 975 error = PTR_ERR(entry); 976 goto failed; 977 } 978 swap = *entry; 979 980 if (swap.val) { 981 /* Look it up and read it in.. */ 982 swappage = lookup_swap_cache(swap); 983 if (!swappage) { 984 shmem_swp_unmap(entry); 985 spin_unlock(&info->lock); 986 /* here we actually do the io */ 987 if (type && *type == VM_FAULT_MINOR) { 988 inc_page_state(pgmajfault); 989 *type = VM_FAULT_MAJOR; 990 } 991 swappage = shmem_swapin(info, swap, idx); 992 if (!swappage) { 993 spin_lock(&info->lock); 994 entry = shmem_swp_alloc(info, idx, sgp); 995 if (IS_ERR(entry)) 996 error = PTR_ERR(entry); 997 else { 998 if (entry->val == swap.val) 999 error = -ENOMEM; 1000 shmem_swp_unmap(entry); 1001 } 1002 spin_unlock(&info->lock); 1003 if (error) 1004 goto failed; 1005 goto repeat; 1006 } 1007 wait_on_page_locked(swappage); 1008 page_cache_release(swappage); 1009 goto repeat; 1010 } 1011 1012 /* We have to do this with page locked to prevent races */ 1013 if (TestSetPageLocked(swappage)) { 1014 shmem_swp_unmap(entry); 1015 spin_unlock(&info->lock); 1016 wait_on_page_locked(swappage); 1017 page_cache_release(swappage); 1018 goto repeat; 1019 } 1020 if (PageWriteback(swappage)) { 1021 shmem_swp_unmap(entry); 1022 spin_unlock(&info->lock); 1023 wait_on_page_writeback(swappage); 1024 unlock_page(swappage); 1025 page_cache_release(swappage); 1026 goto repeat; 1027 } 1028 if (!PageUptodate(swappage)) { 1029 shmem_swp_unmap(entry); 1030 spin_unlock(&info->lock); 1031 unlock_page(swappage); 1032 page_cache_release(swappage); 1033 error = -EIO; 1034 goto failed; 1035 } 1036 1037 if (filepage) { 1038 shmem_swp_set(info, entry, 0); 1039 shmem_swp_unmap(entry); 1040 delete_from_swap_cache(swappage); 1041 spin_unlock(&info->lock); 1042 copy_highpage(filepage, swappage); 1043 unlock_page(swappage); 1044 page_cache_release(swappage); 1045 flush_dcache_page(filepage); 1046 SetPageUptodate(filepage); 1047 set_page_dirty(filepage); 1048 swap_free(swap); 1049 } else if (!(error = move_from_swap_cache( 1050 swappage, idx, mapping))) { 1051 info->flags |= SHMEM_PAGEIN; 1052 shmem_swp_set(info, entry, 0); 1053 shmem_swp_unmap(entry); 1054 spin_unlock(&info->lock); 1055 filepage = swappage; 1056 swap_free(swap); 1057 } else { 1058 shmem_swp_unmap(entry); 1059 spin_unlock(&info->lock); 1060 unlock_page(swappage); 1061 page_cache_release(swappage); 1062 if (error == -ENOMEM) { 1063 /* let kswapd refresh zone for GFP_ATOMICs */ 1064 blk_congestion_wait(WRITE, HZ/50); 1065 } 1066 goto repeat; 1067 } 1068 } else if (sgp == SGP_READ && !filepage) { 1069 shmem_swp_unmap(entry); 1070 filepage = find_get_page(mapping, idx); 1071 if (filepage && 1072 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1073 spin_unlock(&info->lock); 1074 wait_on_page_locked(filepage); 1075 page_cache_release(filepage); 1076 filepage = NULL; 1077 goto repeat; 1078 } 1079 spin_unlock(&info->lock); 1080 } else { 1081 shmem_swp_unmap(entry); 1082 sbinfo = SHMEM_SB(inode->i_sb); 1083 if (sbinfo) { 1084 spin_lock(&sbinfo->stat_lock); 1085 if (sbinfo->free_blocks == 0 || 1086 shmem_acct_block(info->flags)) { 1087 spin_unlock(&sbinfo->stat_lock); 1088 spin_unlock(&info->lock); 1089 error = -ENOSPC; 1090 goto failed; 1091 } 1092 sbinfo->free_blocks--; 1093 inode->i_blocks += BLOCKS_PER_PAGE; 1094 spin_unlock(&sbinfo->stat_lock); 1095 } else if (shmem_acct_block(info->flags)) { 1096 spin_unlock(&info->lock); 1097 error = -ENOSPC; 1098 goto failed; 1099 } 1100 1101 if (!filepage) { 1102 spin_unlock(&info->lock); 1103 filepage = shmem_alloc_page(mapping_gfp_mask(mapping), 1104 info, 1105 idx); 1106 if (!filepage) { 1107 shmem_unacct_blocks(info->flags, 1); 1108 shmem_free_blocks(inode, 1); 1109 error = -ENOMEM; 1110 goto failed; 1111 } 1112 1113 spin_lock(&info->lock); 1114 entry = shmem_swp_alloc(info, idx, sgp); 1115 if (IS_ERR(entry)) 1116 error = PTR_ERR(entry); 1117 else { 1118 swap = *entry; 1119 shmem_swp_unmap(entry); 1120 } 1121 if (error || swap.val || 0 != add_to_page_cache_lru( 1122 filepage, mapping, idx, GFP_ATOMIC)) { 1123 spin_unlock(&info->lock); 1124 page_cache_release(filepage); 1125 shmem_unacct_blocks(info->flags, 1); 1126 shmem_free_blocks(inode, 1); 1127 filepage = NULL; 1128 if (error) 1129 goto failed; 1130 goto repeat; 1131 } 1132 info->flags |= SHMEM_PAGEIN; 1133 } 1134 1135 info->alloced++; 1136 spin_unlock(&info->lock); 1137 flush_dcache_page(filepage); 1138 SetPageUptodate(filepage); 1139 } 1140done: 1141 if (*pagep != filepage) { 1142 unlock_page(filepage); 1143 *pagep = filepage; 1144 } 1145 return 0; 1146 1147failed: 1148 if (*pagep != filepage) { 1149 unlock_page(filepage); 1150 page_cache_release(filepage); 1151 } 1152 return error; 1153} 1154 1155struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type) 1156{ 1157 struct inode *inode = vma->vm_file->f_dentry->d_inode; 1158 struct page *page = NULL; 1159 unsigned long idx; 1160 int error; 1161 1162 idx = (address - vma->vm_start) >> PAGE_SHIFT; 1163 idx += vma->vm_pgoff; 1164 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT; 1165 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1166 return NOPAGE_SIGBUS; 1167 1168 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type); 1169 if (error) 1170 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS; 1171 1172 mark_page_accessed(page); 1173 return page; 1174} 1175 1176static int shmem_populate(struct vm_area_struct *vma, 1177 unsigned long addr, unsigned long len, 1178 pgprot_t prot, unsigned long pgoff, int nonblock) 1179{ 1180 struct inode *inode = vma->vm_file->f_dentry->d_inode; 1181 struct mm_struct *mm = vma->vm_mm; 1182 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE; 1183 unsigned long size; 1184 1185 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; 1186 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size) 1187 return -EINVAL; 1188 1189 while ((long) len > 0) { 1190 struct page *page = NULL; 1191 int err; 1192 /* 1193 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE 1194 */ 1195 err = shmem_getpage(inode, pgoff, &page, sgp, NULL); 1196 if (err) 1197 return err; 1198 if (page) { 1199 mark_page_accessed(page); 1200 err = install_page(mm, vma, addr, page, prot); 1201 if (err) { 1202 page_cache_release(page); 1203 return err; 1204 } 1205 } else if (nonblock) { 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 1219int 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 1225struct mempolicy * 1226shmem_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 1236int 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; 1253out_nomem: 1254 spin_unlock(&info->lock); 1255 return retval; 1256} 1257 1258static 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 1265static struct inode * 1266shmem_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) { 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 inode->i_op = &shmem_special_inode_operations; 1300 init_special_inode(inode, mode, dev); 1301 break; 1302 case S_IFREG: 1303 inode->i_op = &shmem_inode_operations; 1304 inode->i_fop = &shmem_file_operations; 1305 mpol_shared_policy_init(&info->policy); 1306 break; 1307 case S_IFDIR: 1308 inode->i_nlink++; 1309 /* Some things misbehave if size == 0 on a directory */ 1310 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1311 inode->i_op = &shmem_dir_inode_operations; 1312 inode->i_fop = &simple_dir_operations; 1313 break; 1314 case S_IFLNK: 1315 /* 1316 * Must not load anything in the rbtree, 1317 * mpol_free_shared_policy will not be called. 1318 */ 1319 mpol_shared_policy_init(&info->policy); 1320 break; 1321 } 1322 } else if (sbinfo) { 1323 spin_lock(&sbinfo->stat_lock); 1324 sbinfo->free_inodes++; 1325 spin_unlock(&sbinfo->stat_lock); 1326 } 1327 return inode; 1328} 1329 1330#ifdef CONFIG_TMPFS 1331 1332static int shmem_set_size(struct shmem_sb_info *sbinfo, 1333 unsigned long max_blocks, unsigned long max_inodes) 1334{ 1335 int error; 1336 unsigned long blocks, inodes; 1337 1338 spin_lock(&sbinfo->stat_lock); 1339 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 1340 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 1341 error = -EINVAL; 1342 if (max_blocks < blocks) 1343 goto out; 1344 if (max_inodes < inodes) 1345 goto out; 1346 error = 0; 1347 sbinfo->max_blocks = max_blocks; 1348 sbinfo->free_blocks = max_blocks - blocks; 1349 sbinfo->max_inodes = max_inodes; 1350 sbinfo->free_inodes = max_inodes - inodes; 1351out: 1352 spin_unlock(&sbinfo->stat_lock); 1353 return error; 1354} 1355 1356static struct inode_operations shmem_symlink_inode_operations; 1357static struct inode_operations shmem_symlink_inline_operations; 1358 1359/* 1360 * Normally tmpfs makes no use of shmem_prepare_write, but it 1361 * lets a tmpfs file be used read-write below the loop driver. 1362 */ 1363static int 1364shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to) 1365{ 1366 struct inode *inode = page->mapping->host; 1367 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL); 1368} 1369 1370static ssize_t 1371shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 1372{ 1373 struct inode *inode = file->f_dentry->d_inode; 1374 loff_t pos; 1375 unsigned long written; 1376 ssize_t err; 1377 1378 if ((ssize_t) count < 0) 1379 return -EINVAL; 1380 1381 if (!access_ok(VERIFY_READ, buf, count)) 1382 return -EFAULT; 1383 1384 down(&inode->i_sem); 1385 1386 pos = *ppos; 1387 written = 0; 1388 1389 err = generic_write_checks(file, &pos, &count, 0); 1390 if (err || !count) 1391 goto out; 1392 1393 err = remove_suid(file->f_dentry); 1394 if (err) 1395 goto out; 1396 1397 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 1398 1399 do { 1400 struct page *page = NULL; 1401 unsigned long bytes, index, offset; 1402 char *kaddr; 1403 int left; 1404 1405 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1406 index = pos >> PAGE_CACHE_SHIFT; 1407 bytes = PAGE_CACHE_SIZE - offset; 1408 if (bytes > count) 1409 bytes = count; 1410 1411 /* 1412 * We don't hold page lock across copy from user - 1413 * what would it guard against? - so no deadlock here. 1414 * But it still may be a good idea to prefault below. 1415 */ 1416 1417 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL); 1418 if (err) 1419 break; 1420 1421 left = bytes; 1422 if (PageHighMem(page)) { 1423 volatile unsigned char dummy; 1424 __get_user(dummy, buf); 1425 __get_user(dummy, buf + bytes - 1); 1426 1427 kaddr = kmap_atomic(page, KM_USER0); 1428 left = __copy_from_user_inatomic(kaddr + offset, 1429 buf, bytes); 1430 kunmap_atomic(kaddr, KM_USER0); 1431 } 1432 if (left) { 1433 kaddr = kmap(page); 1434 left = __copy_from_user(kaddr + offset, buf, bytes); 1435 kunmap(page); 1436 } 1437 1438 written += bytes; 1439 count -= bytes; 1440 pos += bytes; 1441 buf += bytes; 1442 if (pos > inode->i_size) 1443 i_size_write(inode, pos); 1444 1445 flush_dcache_page(page); 1446 set_page_dirty(page); 1447 mark_page_accessed(page); 1448 page_cache_release(page); 1449 1450 if (left) { 1451 pos -= left; 1452 written -= left; 1453 err = -EFAULT; 1454 break; 1455 } 1456 1457 /* 1458 * Our dirty pages are not counted in nr_dirty, 1459 * and we do not attempt to balance dirty pages. 1460 */ 1461 1462 cond_resched(); 1463 } while (count); 1464 1465 *ppos = pos; 1466 if (written) 1467 err = written; 1468out: 1469 up(&inode->i_sem); 1470 return err; 1471} 1472 1473static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1474{ 1475 struct inode *inode = filp->f_dentry->d_inode; 1476 struct address_space *mapping = inode->i_mapping; 1477 unsigned long index, offset; 1478 1479 index = *ppos >> PAGE_CACHE_SHIFT; 1480 offset = *ppos & ~PAGE_CACHE_MASK; 1481 1482 for (;;) { 1483 struct page *page = NULL; 1484 unsigned long end_index, nr, ret; 1485 loff_t i_size = i_size_read(inode); 1486 1487 end_index = i_size >> PAGE_CACHE_SHIFT; 1488 if (index > end_index) 1489 break; 1490 if (index == end_index) { 1491 nr = i_size & ~PAGE_CACHE_MASK; 1492 if (nr <= offset) 1493 break; 1494 } 1495 1496 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL); 1497 if (desc->error) { 1498 if (desc->error == -EINVAL) 1499 desc->error = 0; 1500 break; 1501 } 1502 1503 /* 1504 * We must evaluate after, since reads (unlike writes) 1505 * are called without i_sem protection against truncate 1506 */ 1507 nr = PAGE_CACHE_SIZE; 1508 i_size = i_size_read(inode); 1509 end_index = i_size >> PAGE_CACHE_SHIFT; 1510 if (index == end_index) { 1511 nr = i_size & ~PAGE_CACHE_MASK; 1512 if (nr <= offset) { 1513 if (page) 1514 page_cache_release(page); 1515 break; 1516 } 1517 } 1518 nr -= offset; 1519 1520 if (page) { 1521 /* 1522 * If users can be writing to this page using arbitrary 1523 * virtual addresses, take care about potential aliasing 1524 * before reading the page on the kernel side. 1525 */ 1526 if (mapping_writably_mapped(mapping)) 1527 flush_dcache_page(page); 1528 /* 1529 * Mark the page accessed if we read the beginning. 1530 */ 1531 if (!offset) 1532 mark_page_accessed(page); 1533 } else 1534 page = ZERO_PAGE(0); 1535 1536 /* 1537 * Ok, we have the page, and it's up-to-date, so 1538 * now we can copy it to user space... 1539 * 1540 * The actor routine returns how many bytes were actually used.. 1541 * NOTE! This may not be the same as how much of a user buffer 1542 * we filled up (we may be padding etc), so we can only update 1543 * "pos" here (the actor routine has to update the user buffer 1544 * pointers and the remaining count). 1545 */ 1546 ret = actor(desc, page, offset, nr); 1547 offset += ret; 1548 index += offset >> PAGE_CACHE_SHIFT; 1549 offset &= ~PAGE_CACHE_MASK; 1550 1551 page_cache_release(page); 1552 if (ret != nr || !desc->count) 1553 break; 1554 1555 cond_resched(); 1556 } 1557 1558 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1559 file_accessed(filp); 1560} 1561 1562static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1563{ 1564 read_descriptor_t desc; 1565 1566 if ((ssize_t) count < 0) 1567 return -EINVAL; 1568 if (!access_ok(VERIFY_WRITE, buf, count)) 1569 return -EFAULT; 1570 if (!count) 1571 return 0; 1572 1573 desc.written = 0; 1574 desc.count = count; 1575 desc.arg.buf = buf; 1576 desc.error = 0; 1577 1578 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1579 if (desc.written) 1580 return desc.written; 1581 return desc.error; 1582} 1583 1584static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos, 1585 size_t count, read_actor_t actor, void *target) 1586{ 1587 read_descriptor_t desc; 1588 1589 if (!count) 1590 return 0; 1591 1592 desc.written = 0; 1593 desc.count = count; 1594 desc.arg.data = target; 1595 desc.error = 0; 1596 1597 do_shmem_file_read(in_file, ppos, &desc, actor); 1598 if (desc.written) 1599 return desc.written; 1600 return desc.error; 1601} 1602 1603static int shmem_statfs(struct super_block *sb, struct kstatfs *buf) 1604{ 1605 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1606 1607 buf->f_type = TMPFS_MAGIC; 1608 buf->f_bsize = PAGE_CACHE_SIZE; 1609 buf->f_namelen = NAME_MAX; 1610 if (sbinfo) { 1611 spin_lock(&sbinfo->stat_lock); 1612 buf->f_blocks = sbinfo->max_blocks; 1613 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1614 buf->f_files = sbinfo->max_inodes; 1615 buf->f_ffree = sbinfo->free_inodes; 1616 spin_unlock(&sbinfo->stat_lock); 1617 } 1618 /* else leave those fields 0 like simple_statfs */ 1619 return 0; 1620} 1621 1622/* 1623 * File creation. Allocate an inode, and we're done.. 1624 */ 1625static int 1626shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1627{ 1628 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1629 int error = -ENOSPC; 1630 1631 if (inode) { 1632 if (dir->i_mode & S_ISGID) { 1633 inode->i_gid = dir->i_gid; 1634 if (S_ISDIR(mode)) 1635 inode->i_mode |= S_ISGID; 1636 } 1637 dir->i_size += BOGO_DIRENT_SIZE; 1638 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1639 d_instantiate(dentry, inode); 1640 dget(dentry); /* Extra count - pin the dentry in core */ 1641 error = 0; 1642 } 1643 return error; 1644} 1645 1646static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1647{ 1648 int error; 1649 1650 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1651 return error; 1652 dir->i_nlink++; 1653 return 0; 1654} 1655 1656static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1657 struct nameidata *nd) 1658{ 1659 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1660} 1661 1662/* 1663 * Link a file.. 1664 */ 1665static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1666{ 1667 struct inode *inode = old_dentry->d_inode; 1668 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1669 1670 /* 1671 * No ordinary (disk based) filesystem counts links as inodes; 1672 * but each new link needs a new dentry, pinning lowmem, and 1673 * tmpfs dentries cannot be pruned until they are unlinked. 1674 */ 1675 if (sbinfo) { 1676 spin_lock(&sbinfo->stat_lock); 1677 if (!sbinfo->free_inodes) { 1678 spin_unlock(&sbinfo->stat_lock); 1679 return -ENOSPC; 1680 } 1681 sbinfo->free_inodes--; 1682 spin_unlock(&sbinfo->stat_lock); 1683 } 1684 1685 dir->i_size += BOGO_DIRENT_SIZE; 1686 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1687 inode->i_nlink++; 1688 atomic_inc(&inode->i_count); /* New dentry reference */ 1689 dget(dentry); /* Extra pinning count for the created dentry */ 1690 d_instantiate(dentry, inode); 1691 return 0; 1692} 1693 1694static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1695{ 1696 struct inode *inode = dentry->d_inode; 1697 1698 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) { 1699 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1700 if (sbinfo) { 1701 spin_lock(&sbinfo->stat_lock); 1702 sbinfo->free_inodes++; 1703 spin_unlock(&sbinfo->stat_lock); 1704 } 1705 } 1706 1707 dir->i_size -= BOGO_DIRENT_SIZE; 1708 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1709 inode->i_nlink--; 1710 dput(dentry); /* Undo the count from "create" - this does all the work */ 1711 return 0; 1712} 1713 1714static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1715{ 1716 if (!simple_empty(dentry)) 1717 return -ENOTEMPTY; 1718 1719 dir->i_nlink--; 1720 return shmem_unlink(dir, dentry); 1721} 1722 1723/* 1724 * The VFS layer already does all the dentry stuff for rename, 1725 * we just have to decrement the usage count for the target if 1726 * it exists so that the VFS layer correctly free's it when it 1727 * gets overwritten. 1728 */ 1729static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1730{ 1731 struct inode *inode = old_dentry->d_inode; 1732 int they_are_dirs = S_ISDIR(inode->i_mode); 1733 1734 if (!simple_empty(new_dentry)) 1735 return -ENOTEMPTY; 1736 1737 if (new_dentry->d_inode) { 1738 (void) shmem_unlink(new_dir, new_dentry); 1739 if (they_are_dirs) 1740 old_dir->i_nlink--; 1741 } else if (they_are_dirs) { 1742 old_dir->i_nlink--; 1743 new_dir->i_nlink++; 1744 } 1745 1746 old_dir->i_size -= BOGO_DIRENT_SIZE; 1747 new_dir->i_size += BOGO_DIRENT_SIZE; 1748 old_dir->i_ctime = old_dir->i_mtime = 1749 new_dir->i_ctime = new_dir->i_mtime = 1750 inode->i_ctime = CURRENT_TIME; 1751 return 0; 1752} 1753 1754static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1755{ 1756 int error; 1757 int len; 1758 struct inode *inode; 1759 struct page *page = NULL; 1760 char *kaddr; 1761 struct shmem_inode_info *info; 1762 1763 len = strlen(symname) + 1; 1764 if (len > PAGE_CACHE_SIZE) 1765 return -ENAMETOOLONG; 1766 1767 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1768 if (!inode) 1769 return -ENOSPC; 1770 1771 info = SHMEM_I(inode); 1772 inode->i_size = len-1; 1773 if (len <= (char *)inode - (char *)info) { 1774 /* do it inline */ 1775 memcpy(info, symname, len); 1776 inode->i_op = &shmem_symlink_inline_operations; 1777 } else { 1778 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1779 if (error) { 1780 iput(inode); 1781 return error; 1782 } 1783 inode->i_op = &shmem_symlink_inode_operations; 1784 kaddr = kmap_atomic(page, KM_USER0); 1785 memcpy(kaddr, symname, len); 1786 kunmap_atomic(kaddr, KM_USER0); 1787 set_page_dirty(page); 1788 page_cache_release(page); 1789 } 1790 if (dir->i_mode & S_ISGID) 1791 inode->i_gid = dir->i_gid; 1792 dir->i_size += BOGO_DIRENT_SIZE; 1793 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1794 d_instantiate(dentry, inode); 1795 dget(dentry); 1796 return 0; 1797} 1798 1799static int shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1800{ 1801 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1802 return 0; 1803} 1804 1805static int shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1806{ 1807 struct page *page = NULL; 1808 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1809 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1810 return 0; 1811} 1812 1813static void shmem_put_link(struct dentry *dentry, struct nameidata *nd) 1814{ 1815 if (!IS_ERR(nd_get_link(nd))) { 1816 struct page *page; 1817 1818 page = find_get_page(dentry->d_inode->i_mapping, 0); 1819 if (!page) 1820 BUG(); 1821 kunmap(page); 1822 mark_page_accessed(page); 1823 page_cache_release(page); 1824 page_cache_release(page); 1825 } 1826} 1827 1828static struct inode_operations shmem_symlink_inline_operations = { 1829 .readlink = generic_readlink, 1830 .follow_link = shmem_follow_link_inline, 1831#ifdef CONFIG_TMPFS_XATTR 1832 .setxattr = generic_setxattr, 1833 .getxattr = generic_getxattr, 1834 .listxattr = generic_listxattr, 1835 .removexattr = generic_removexattr, 1836#endif 1837}; 1838 1839static struct inode_operations shmem_symlink_inode_operations = { 1840 .truncate = shmem_truncate, 1841 .readlink = generic_readlink, 1842 .follow_link = shmem_follow_link, 1843 .put_link = shmem_put_link, 1844#ifdef CONFIG_TMPFS_XATTR 1845 .setxattr = generic_setxattr, 1846 .getxattr = generic_getxattr, 1847 .listxattr = generic_listxattr, 1848 .removexattr = generic_removexattr, 1849#endif 1850}; 1851 1852static int shmem_parse_options(char *options, int *mode, uid_t *uid, gid_t *gid, unsigned long *blocks, unsigned long *inodes) 1853{ 1854 char *this_char, *value, *rest; 1855 1856 while ((this_char = strsep(&options, ",")) != NULL) { 1857 if (!*this_char) 1858 continue; 1859 if ((value = strchr(this_char,'=')) != NULL) { 1860 *value++ = 0; 1861 } else { 1862 printk(KERN_ERR 1863 "tmpfs: No value for mount option '%s'\n", 1864 this_char); 1865 return 1; 1866 } 1867 1868 if (!strcmp(this_char,"size")) { 1869 unsigned long long size; 1870 size = memparse(value,&rest); 1871 if (*rest == '%') { 1872 size <<= PAGE_SHIFT; 1873 size *= totalram_pages; 1874 do_div(size, 100); 1875 rest++; 1876 } 1877 if (*rest) 1878 goto bad_val; 1879 *blocks = size >> PAGE_CACHE_SHIFT; 1880 } else if (!strcmp(this_char,"nr_blocks")) { 1881 *blocks = memparse(value,&rest); 1882 if (*rest) 1883 goto bad_val; 1884 } else if (!strcmp(this_char,"nr_inodes")) { 1885 *inodes = memparse(value,&rest); 1886 if (*rest) 1887 goto bad_val; 1888 } else if (!strcmp(this_char,"mode")) { 1889 if (!mode) 1890 continue; 1891 *mode = simple_strtoul(value,&rest,8); 1892 if (*rest) 1893 goto bad_val; 1894 } else if (!strcmp(this_char,"uid")) { 1895 if (!uid) 1896 continue; 1897 *uid = simple_strtoul(value,&rest,0); 1898 if (*rest) 1899 goto bad_val; 1900 } else if (!strcmp(this_char,"gid")) { 1901 if (!gid) 1902 continue; 1903 *gid = simple_strtoul(value,&rest,0); 1904 if (*rest) 1905 goto bad_val; 1906 } else { 1907 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 1908 this_char); 1909 return 1; 1910 } 1911 } 1912 return 0; 1913 1914bad_val: 1915 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 1916 value, this_char); 1917 return 1; 1918 1919} 1920 1921static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 1922{ 1923 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1924 unsigned long max_blocks = 0; 1925 unsigned long max_inodes = 0; 1926 1927 if (sbinfo) { 1928 max_blocks = sbinfo->max_blocks; 1929 max_inodes = sbinfo->max_inodes; 1930 } 1931 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, &max_inodes)) 1932 return -EINVAL; 1933 /* Keep it simple: disallow limited <-> unlimited remount */ 1934 if ((max_blocks || max_inodes) == !sbinfo) 1935 return -EINVAL; 1936 /* But allow the pointless unlimited -> unlimited remount */ 1937 if (!sbinfo) 1938 return 0; 1939 return shmem_set_size(sbinfo, max_blocks, max_inodes); 1940} 1941#endif 1942 1943static void shmem_put_super(struct super_block *sb) 1944{ 1945 kfree(sb->s_fs_info); 1946 sb->s_fs_info = NULL; 1947} 1948 1949#ifdef CONFIG_TMPFS_XATTR 1950static struct xattr_handler *shmem_xattr_handlers[]; 1951#else 1952#define shmem_xattr_handlers NULL 1953#endif 1954 1955static int shmem_fill_super(struct super_block *sb, 1956 void *data, int silent) 1957{ 1958 struct inode *inode; 1959 struct dentry *root; 1960 int mode = S_IRWXUGO | S_ISVTX; 1961 uid_t uid = current->fsuid; 1962 gid_t gid = current->fsgid; 1963 int err = -ENOMEM; 1964 1965#ifdef CONFIG_TMPFS 1966 unsigned long blocks = 0; 1967 unsigned long inodes = 0; 1968 1969 /* 1970 * Per default we only allow half of the physical ram per 1971 * tmpfs instance, limiting inodes to one per page of lowmem; 1972 * but the internal instance is left unlimited. 1973 */ 1974 if (!(sb->s_flags & MS_NOUSER)) { 1975 blocks = totalram_pages / 2; 1976 inodes = totalram_pages - totalhigh_pages; 1977 if (inodes > blocks) 1978 inodes = blocks; 1979 1980 if (shmem_parse_options(data, &mode, 1981 &uid, &gid, &blocks, &inodes)) 1982 return -EINVAL; 1983 } 1984 1985 if (blocks || inodes) { 1986 struct shmem_sb_info *sbinfo; 1987 sbinfo = kmalloc(sizeof(struct shmem_sb_info), GFP_KERNEL); 1988 if (!sbinfo) 1989 return -ENOMEM; 1990 sb->s_fs_info = sbinfo; 1991 spin_lock_init(&sbinfo->stat_lock); 1992 sbinfo->max_blocks = blocks; 1993 sbinfo->free_blocks = blocks; 1994 sbinfo->max_inodes = inodes; 1995 sbinfo->free_inodes = inodes; 1996 } 1997 sb->s_xattr = shmem_xattr_handlers; 1998#else 1999 sb->s_flags |= MS_NOUSER; 2000#endif 2001 2002 sb->s_maxbytes = SHMEM_MAX_BYTES; 2003 sb->s_blocksize = PAGE_CACHE_SIZE; 2004 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2005 sb->s_magic = TMPFS_MAGIC; 2006 sb->s_op = &shmem_ops; 2007 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 2008 if (!inode) 2009 goto failed; 2010 inode->i_uid = uid; 2011 inode->i_gid = gid; 2012 root = d_alloc_root(inode); 2013 if (!root) 2014 goto failed_iput; 2015 sb->s_root = root; 2016 return 0; 2017 2018failed_iput: 2019 iput(inode); 2020failed: 2021 shmem_put_super(sb); 2022 return err; 2023} 2024 2025static kmem_cache_t *shmem_inode_cachep; 2026 2027static struct inode *shmem_alloc_inode(struct super_block *sb) 2028{ 2029 struct shmem_inode_info *p; 2030 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL); 2031 if (!p) 2032 return NULL; 2033 return &p->vfs_inode; 2034} 2035 2036static void shmem_destroy_inode(struct inode *inode) 2037{ 2038 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2039 /* only struct inode is valid if it's an inline symlink */ 2040 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2041 } 2042 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2043} 2044 2045static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags) 2046{ 2047 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2048 2049 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == 2050 SLAB_CTOR_CONSTRUCTOR) { 2051 inode_init_once(&p->vfs_inode); 2052 } 2053} 2054 2055static int init_inodecache(void) 2056{ 2057 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2058 sizeof(struct shmem_inode_info), 2059 0, 0, init_once, NULL); 2060 if (shmem_inode_cachep == NULL) 2061 return -ENOMEM; 2062 return 0; 2063} 2064 2065static void destroy_inodecache(void) 2066{ 2067 if (kmem_cache_destroy(shmem_inode_cachep)) 2068 printk(KERN_INFO "shmem_inode_cache: not all structures were freed\n"); 2069} 2070 2071static struct address_space_operations shmem_aops = { 2072 .writepage = shmem_writepage, 2073 .set_page_dirty = __set_page_dirty_nobuffers, 2074#ifdef CONFIG_TMPFS 2075 .prepare_write = shmem_prepare_write, 2076 .commit_write = simple_commit_write, 2077#endif 2078}; 2079 2080static struct file_operations shmem_file_operations = { 2081 .mmap = shmem_mmap, 2082#ifdef CONFIG_TMPFS 2083 .llseek = generic_file_llseek, 2084 .read = shmem_file_read, 2085 .write = shmem_file_write, 2086 .fsync = simple_sync_file, 2087 .sendfile = shmem_file_sendfile, 2088#endif 2089}; 2090 2091static struct inode_operations shmem_inode_operations = { 2092 .truncate = shmem_truncate, 2093 .setattr = shmem_notify_change, 2094#ifdef CONFIG_TMPFS_XATTR 2095 .setxattr = generic_setxattr, 2096 .getxattr = generic_getxattr, 2097 .listxattr = generic_listxattr, 2098 .removexattr = generic_removexattr, 2099#endif 2100}; 2101 2102static struct inode_operations shmem_dir_inode_operations = { 2103#ifdef CONFIG_TMPFS 2104 .create = shmem_create, 2105 .lookup = simple_lookup, 2106 .link = shmem_link, 2107 .unlink = shmem_unlink, 2108 .symlink = shmem_symlink, 2109 .mkdir = shmem_mkdir, 2110 .rmdir = shmem_rmdir, 2111 .mknod = shmem_mknod, 2112 .rename = shmem_rename, 2113#ifdef CONFIG_TMPFS_XATTR 2114 .setxattr = generic_setxattr, 2115 .getxattr = generic_getxattr, 2116 .listxattr = generic_listxattr, 2117 .removexattr = generic_removexattr, 2118#endif 2119#endif 2120}; 2121 2122static struct inode_operations shmem_special_inode_operations = { 2123#ifdef CONFIG_TMPFS_XATTR 2124 .setxattr = generic_setxattr, 2125 .getxattr = generic_getxattr, 2126 .listxattr = generic_listxattr, 2127 .removexattr = generic_removexattr, 2128#endif 2129}; 2130 2131static struct super_operations shmem_ops = { 2132 .alloc_inode = shmem_alloc_inode, 2133 .destroy_inode = shmem_destroy_inode, 2134#ifdef CONFIG_TMPFS 2135 .statfs = shmem_statfs, 2136 .remount_fs = shmem_remount_fs, 2137#endif 2138 .delete_inode = shmem_delete_inode, 2139 .drop_inode = generic_delete_inode, 2140 .put_super = shmem_put_super, 2141}; 2142 2143static struct vm_operations_struct shmem_vm_ops = { 2144 .nopage = shmem_nopage, 2145 .populate = shmem_populate, 2146#ifdef CONFIG_NUMA 2147 .set_policy = shmem_set_policy, 2148 .get_policy = shmem_get_policy, 2149#endif 2150}; 2151 2152 2153#ifdef CONFIG_TMPFS_SECURITY 2154 2155static size_t shmem_xattr_security_list(struct inode *inode, char *list, size_t list_len, 2156 const char *name, size_t name_len) 2157{ 2158 return security_inode_listsecurity(inode, list, list_len); 2159} 2160 2161static int shmem_xattr_security_get(struct inode *inode, const char *name, void *buffer, size_t size) 2162{ 2163 if (strcmp(name, "") == 0) 2164 return -EINVAL; 2165 return security_inode_getsecurity(inode, name, buffer, size); 2166} 2167 2168static int shmem_xattr_security_set(struct inode *inode, const char *name, const void *value, size_t size, int flags) 2169{ 2170 if (strcmp(name, "") == 0) 2171 return -EINVAL; 2172 return security_inode_setsecurity(inode, name, value, size, flags); 2173} 2174 2175static struct xattr_handler shmem_xattr_security_handler = { 2176 .prefix = XATTR_SECURITY_PREFIX, 2177 .list = shmem_xattr_security_list, 2178 .get = shmem_xattr_security_get, 2179 .set = shmem_xattr_security_set, 2180}; 2181 2182#endif /* CONFIG_TMPFS_SECURITY */ 2183 2184#ifdef CONFIG_TMPFS_XATTR 2185 2186static struct xattr_handler *shmem_xattr_handlers[] = { 2187#ifdef CONFIG_TMPFS_SECURITY 2188 &shmem_xattr_security_handler, 2189#endif 2190 NULL 2191}; 2192 2193#endif /* CONFIG_TMPFS_XATTR */ 2194 2195static struct super_block *shmem_get_sb(struct file_system_type *fs_type, 2196 int flags, const char *dev_name, void *data) 2197{ 2198 return get_sb_nodev(fs_type, flags, data, shmem_fill_super); 2199} 2200 2201static struct file_system_type tmpfs_fs_type = { 2202 .owner = THIS_MODULE, 2203 .name = "tmpfs", 2204 .get_sb = shmem_get_sb, 2205 .kill_sb = kill_litter_super, 2206}; 2207static struct vfsmount *shm_mnt; 2208 2209static int __init init_tmpfs(void) 2210{ 2211 int error; 2212 2213 error = init_inodecache(); 2214 if (error) 2215 goto out3; 2216 2217 error = register_filesystem(&tmpfs_fs_type); 2218 if (error) { 2219 printk(KERN_ERR "Could not register tmpfs\n"); 2220 goto out2; 2221 } 2222#ifdef CONFIG_TMPFS 2223 devfs_mk_dir("shm"); 2224#endif 2225 shm_mnt = do_kern_mount(tmpfs_fs_type.name, MS_NOUSER, 2226 tmpfs_fs_type.name, NULL); 2227 if (IS_ERR(shm_mnt)) { 2228 error = PTR_ERR(shm_mnt); 2229 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2230 goto out1; 2231 } 2232 return 0; 2233 2234out1: 2235 unregister_filesystem(&tmpfs_fs_type); 2236out2: 2237 destroy_inodecache(); 2238out3: 2239 shm_mnt = ERR_PTR(error); 2240 return error; 2241} 2242module_init(init_tmpfs) 2243 2244/* 2245 * shmem_file_setup - get an unlinked file living in tmpfs 2246 * 2247 * @name: name for dentry (to be seen in /proc/<pid>/maps 2248 * @size: size to be set for the file 2249 * 2250 */ 2251struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2252{ 2253 int error; 2254 struct file *file; 2255 struct inode *inode; 2256 struct dentry *dentry, *root; 2257 struct qstr this; 2258 2259 if (IS_ERR(shm_mnt)) 2260 return (void *)shm_mnt; 2261 2262 if (size < 0 || size > SHMEM_MAX_BYTES) 2263 return ERR_PTR(-EINVAL); 2264 2265 if (shmem_acct_size(flags, size)) 2266 return ERR_PTR(-ENOMEM); 2267 2268 error = -ENOMEM; 2269 this.name = name; 2270 this.len = strlen(name); 2271 this.hash = 0; /* will go */ 2272 root = shm_mnt->mnt_root; 2273 dentry = d_alloc(root, &this); 2274 if (!dentry) 2275 goto put_memory; 2276 2277 error = -ENFILE; 2278 file = get_empty_filp(); 2279 if (!file) 2280 goto put_dentry; 2281 2282 error = -ENOSPC; 2283 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2284 if (!inode) 2285 goto close_file; 2286 2287 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2288 d_instantiate(dentry, inode); 2289 inode->i_size = size; 2290 inode->i_nlink = 0; /* It is unlinked */ 2291 file->f_vfsmnt = mntget(shm_mnt); 2292 file->f_dentry = dentry; 2293 file->f_mapping = inode->i_mapping; 2294 file->f_op = &shmem_file_operations; 2295 file->f_mode = FMODE_WRITE | FMODE_READ; 2296 return file; 2297 2298close_file: 2299 put_filp(file); 2300put_dentry: 2301 dput(dentry); 2302put_memory: 2303 shmem_unacct_size(flags, size); 2304 return ERR_PTR(error); 2305} 2306 2307/* 2308 * shmem_zero_setup - setup a shared anonymous mapping 2309 * 2310 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2311 */ 2312int shmem_zero_setup(struct vm_area_struct *vma) 2313{ 2314 struct file *file; 2315 loff_t size = vma->vm_end - vma->vm_start; 2316 2317 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2318 if (IS_ERR(file)) 2319 return PTR_ERR(file); 2320 2321 if (vma->vm_file) 2322 fput(vma->vm_file); 2323 vma->vm_file = file; 2324 vma->vm_ops = &shmem_vm_ops; 2325 return 0; 2326} 2327