shmem.c revision fef266580e5cf897a1b63528fc6b1185e2d6bb87
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/* Keep swapped page count in private field of indirect struct page */ 75#define nr_swapped private 76 77/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ 78enum sgp_type { 79 SGP_QUICK, /* don't try more than file page cache lookup */ 80 SGP_READ, /* don't exceed i_size, don't allocate page */ 81 SGP_CACHE, /* don't exceed i_size, may allocate page */ 82 SGP_WRITE, /* may exceed i_size, may allocate page */ 83}; 84 85static int shmem_getpage(struct inode *inode, unsigned long idx, 86 struct page **pagep, enum sgp_type sgp, int *type); 87 88static inline struct page *shmem_dir_alloc(unsigned int gfp_mask) 89{ 90 /* 91 * The above definition of ENTRIES_PER_PAGE, and the use of 92 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 93 * might be reconsidered if it ever diverges from PAGE_SIZE. 94 */ 95 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT); 96} 97 98static inline void shmem_dir_free(struct page *page) 99{ 100 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 101} 102 103static struct page **shmem_dir_map(struct page *page) 104{ 105 return (struct page **)kmap_atomic(page, KM_USER0); 106} 107 108static inline void shmem_dir_unmap(struct page **dir) 109{ 110 kunmap_atomic(dir, KM_USER0); 111} 112 113static swp_entry_t *shmem_swp_map(struct page *page) 114{ 115 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 116} 117 118static inline void shmem_swp_balance_unmap(void) 119{ 120 /* 121 * When passing a pointer to an i_direct entry, to code which 122 * also handles indirect entries and so will shmem_swp_unmap, 123 * we must arrange for the preempt count to remain in balance. 124 * What kmap_atomic of a lowmem page does depends on config 125 * and architecture, so pretend to kmap_atomic some lowmem page. 126 */ 127 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 128} 129 130static inline void shmem_swp_unmap(swp_entry_t *entry) 131{ 132 kunmap_atomic(entry, KM_USER1); 133} 134 135static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 136{ 137 return sb->s_fs_info; 138} 139 140/* 141 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 142 * for shared memory and for shared anonymous (/dev/zero) mappings 143 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 144 * consistent with the pre-accounting of private mappings ... 145 */ 146static inline int shmem_acct_size(unsigned long flags, loff_t size) 147{ 148 return (flags & VM_ACCOUNT)? 149 security_vm_enough_memory(VM_ACCT(size)): 0; 150} 151 152static inline void shmem_unacct_size(unsigned long flags, loff_t size) 153{ 154 if (flags & VM_ACCOUNT) 155 vm_unacct_memory(VM_ACCT(size)); 156} 157 158/* 159 * ... whereas tmpfs objects are accounted incrementally as 160 * pages are allocated, in order to allow huge sparse files. 161 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 162 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 163 */ 164static inline int shmem_acct_block(unsigned long flags) 165{ 166 return (flags & VM_ACCOUNT)? 167 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE)); 168} 169 170static inline void shmem_unacct_blocks(unsigned long flags, long pages) 171{ 172 if (!(flags & VM_ACCOUNT)) 173 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 174} 175 176static struct super_operations shmem_ops; 177static struct address_space_operations shmem_aops; 178static struct file_operations shmem_file_operations; 179static struct inode_operations shmem_inode_operations; 180static struct inode_operations shmem_dir_inode_operations; 181static struct vm_operations_struct shmem_vm_ops; 182 183static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 184 .ra_pages = 0, /* No readahead */ 185 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, 186 .unplug_io_fn = default_unplug_io_fn, 187}; 188 189static LIST_HEAD(shmem_swaplist); 190static DEFINE_SPINLOCK(shmem_swaplist_lock); 191 192static void shmem_free_blocks(struct inode *inode, long pages) 193{ 194 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 195 if (sbinfo->max_blocks) { 196 spin_lock(&sbinfo->stat_lock); 197 sbinfo->free_blocks += pages; 198 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 199 spin_unlock(&sbinfo->stat_lock); 200 } 201} 202 203/* 204 * shmem_recalc_inode - recalculate the size of an inode 205 * 206 * @inode: inode to recalc 207 * 208 * We have to calculate the free blocks since the mm can drop 209 * undirtied hole pages behind our back. 210 * 211 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 212 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 213 * 214 * It has to be called with the spinlock held. 215 */ 216static void shmem_recalc_inode(struct inode *inode) 217{ 218 struct shmem_inode_info *info = SHMEM_I(inode); 219 long freed; 220 221 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 222 if (freed > 0) { 223 info->alloced -= freed; 224 shmem_unacct_blocks(info->flags, freed); 225 shmem_free_blocks(inode, freed); 226 } 227} 228 229/* 230 * shmem_swp_entry - find the swap vector position in the info structure 231 * 232 * @info: info structure for the inode 233 * @index: index of the page to find 234 * @page: optional page to add to the structure. Has to be preset to 235 * all zeros 236 * 237 * If there is no space allocated yet it will return NULL when 238 * page is NULL, else it will use the page for the needed block, 239 * setting it to NULL on return to indicate that it has been used. 240 * 241 * The swap vector is organized the following way: 242 * 243 * There are SHMEM_NR_DIRECT entries directly stored in the 244 * shmem_inode_info structure. So small files do not need an addional 245 * allocation. 246 * 247 * For pages with index > SHMEM_NR_DIRECT there is the pointer 248 * i_indirect which points to a page which holds in the first half 249 * doubly indirect blocks, in the second half triple indirect blocks: 250 * 251 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 252 * following layout (for SHMEM_NR_DIRECT == 16): 253 * 254 * i_indirect -> dir --> 16-19 255 * | +-> 20-23 256 * | 257 * +-->dir2 --> 24-27 258 * | +-> 28-31 259 * | +-> 32-35 260 * | +-> 36-39 261 * | 262 * +-->dir3 --> 40-43 263 * +-> 44-47 264 * +-> 48-51 265 * +-> 52-55 266 */ 267static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 268{ 269 unsigned long offset; 270 struct page **dir; 271 struct page *subdir; 272 273 if (index < SHMEM_NR_DIRECT) { 274 shmem_swp_balance_unmap(); 275 return info->i_direct+index; 276 } 277 if (!info->i_indirect) { 278 if (page) { 279 info->i_indirect = *page; 280 *page = NULL; 281 } 282 return NULL; /* need another page */ 283 } 284 285 index -= SHMEM_NR_DIRECT; 286 offset = index % ENTRIES_PER_PAGE; 287 index /= ENTRIES_PER_PAGE; 288 dir = shmem_dir_map(info->i_indirect); 289 290 if (index >= ENTRIES_PER_PAGE/2) { 291 index -= ENTRIES_PER_PAGE/2; 292 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 293 index %= ENTRIES_PER_PAGE; 294 subdir = *dir; 295 if (!subdir) { 296 if (page) { 297 *dir = *page; 298 *page = NULL; 299 } 300 shmem_dir_unmap(dir); 301 return NULL; /* need another page */ 302 } 303 shmem_dir_unmap(dir); 304 dir = shmem_dir_map(subdir); 305 } 306 307 dir += index; 308 subdir = *dir; 309 if (!subdir) { 310 if (!page || !(subdir = *page)) { 311 shmem_dir_unmap(dir); 312 return NULL; /* need a page */ 313 } 314 *dir = subdir; 315 *page = NULL; 316 } 317 shmem_dir_unmap(dir); 318 return shmem_swp_map(subdir) + offset; 319} 320 321static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 322{ 323 long incdec = value? 1: -1; 324 325 entry->val = value; 326 info->swapped += incdec; 327 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) 328 kmap_atomic_to_page(entry)->nr_swapped += incdec; 329} 330 331/* 332 * shmem_swp_alloc - get the position of the swap entry for the page. 333 * If it does not exist allocate the entry. 334 * 335 * @info: info structure for the inode 336 * @index: index of the page to find 337 * @sgp: check and recheck i_size? skip allocation? 338 */ 339static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 340{ 341 struct inode *inode = &info->vfs_inode; 342 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 343 struct page *page = NULL; 344 swp_entry_t *entry; 345 346 if (sgp != SGP_WRITE && 347 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 348 return ERR_PTR(-EINVAL); 349 350 while (!(entry = shmem_swp_entry(info, index, &page))) { 351 if (sgp == SGP_READ) 352 return shmem_swp_map(ZERO_PAGE(0)); 353 /* 354 * Test free_blocks against 1 not 0, since we have 1 data 355 * page (and perhaps indirect index pages) yet to allocate: 356 * a waste to allocate index if we cannot allocate data. 357 */ 358 if (sbinfo->max_blocks) { 359 spin_lock(&sbinfo->stat_lock); 360 if (sbinfo->free_blocks <= 1) { 361 spin_unlock(&sbinfo->stat_lock); 362 return ERR_PTR(-ENOSPC); 363 } 364 sbinfo->free_blocks--; 365 inode->i_blocks += BLOCKS_PER_PAGE; 366 spin_unlock(&sbinfo->stat_lock); 367 } 368 369 spin_unlock(&info->lock); 370 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO); 371 if (page) { 372 page->nr_swapped = 0; 373 } 374 spin_lock(&info->lock); 375 376 if (!page) { 377 shmem_free_blocks(inode, 1); 378 return ERR_PTR(-ENOMEM); 379 } 380 if (sgp != SGP_WRITE && 381 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 382 entry = ERR_PTR(-EINVAL); 383 break; 384 } 385 if (info->next_index <= index) 386 info->next_index = index + 1; 387 } 388 if (page) { 389 /* another task gave its page, or truncated the file */ 390 shmem_free_blocks(inode, 1); 391 shmem_dir_free(page); 392 } 393 if (info->next_index <= index && !IS_ERR(entry)) 394 info->next_index = index + 1; 395 return entry; 396} 397 398/* 399 * shmem_free_swp - free some swap entries in a directory 400 * 401 * @dir: pointer to the directory 402 * @edir: pointer after last entry of the directory 403 */ 404static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir) 405{ 406 swp_entry_t *ptr; 407 int freed = 0; 408 409 for (ptr = dir; ptr < edir; ptr++) { 410 if (ptr->val) { 411 free_swap_and_cache(*ptr); 412 *ptr = (swp_entry_t){0}; 413 freed++; 414 } 415 } 416 return freed; 417} 418 419static int shmem_map_and_free_swp(struct page *subdir, 420 int offset, int limit, struct page ***dir) 421{ 422 swp_entry_t *ptr; 423 int freed = 0; 424 425 ptr = shmem_swp_map(subdir); 426 for (; offset < limit; offset += LATENCY_LIMIT) { 427 int size = limit - offset; 428 if (size > LATENCY_LIMIT) 429 size = LATENCY_LIMIT; 430 freed += shmem_free_swp(ptr+offset, ptr+offset+size); 431 if (need_resched()) { 432 shmem_swp_unmap(ptr); 433 if (*dir) { 434 shmem_dir_unmap(*dir); 435 *dir = NULL; 436 } 437 cond_resched(); 438 ptr = shmem_swp_map(subdir); 439 } 440 } 441 shmem_swp_unmap(ptr); 442 return freed; 443} 444 445static void shmem_free_pages(struct list_head *next) 446{ 447 struct page *page; 448 int freed = 0; 449 450 do { 451 page = container_of(next, struct page, lru); 452 next = next->next; 453 shmem_dir_free(page); 454 freed++; 455 if (freed >= LATENCY_LIMIT) { 456 cond_resched(); 457 freed = 0; 458 } 459 } while (next); 460} 461 462static void shmem_truncate(struct inode *inode) 463{ 464 struct shmem_inode_info *info = SHMEM_I(inode); 465 unsigned long idx; 466 unsigned long size; 467 unsigned long limit; 468 unsigned long stage; 469 unsigned long diroff; 470 struct page **dir; 471 struct page *topdir; 472 struct page *middir; 473 struct page *subdir; 474 swp_entry_t *ptr; 475 LIST_HEAD(pages_to_free); 476 long nr_pages_to_free = 0; 477 long nr_swaps_freed = 0; 478 int offset; 479 int freed; 480 481 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 482 idx = (inode->i_size + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 483 if (idx >= info->next_index) 484 return; 485 486 spin_lock(&info->lock); 487 info->flags |= SHMEM_TRUNCATE; 488 limit = info->next_index; 489 info->next_index = idx; 490 topdir = info->i_indirect; 491 if (topdir && idx <= SHMEM_NR_DIRECT) { 492 info->i_indirect = NULL; 493 nr_pages_to_free++; 494 list_add(&topdir->lru, &pages_to_free); 495 } 496 spin_unlock(&info->lock); 497 498 if (info->swapped && idx < SHMEM_NR_DIRECT) { 499 ptr = info->i_direct; 500 size = limit; 501 if (size > SHMEM_NR_DIRECT) 502 size = SHMEM_NR_DIRECT; 503 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size); 504 } 505 if (!topdir) 506 goto done2; 507 508 BUG_ON(limit <= SHMEM_NR_DIRECT); 509 limit -= SHMEM_NR_DIRECT; 510 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 511 offset = idx % ENTRIES_PER_PAGE; 512 idx -= offset; 513 514 dir = shmem_dir_map(topdir); 515 stage = ENTRIES_PER_PAGEPAGE/2; 516 if (idx < ENTRIES_PER_PAGEPAGE/2) { 517 middir = topdir; 518 diroff = idx/ENTRIES_PER_PAGE; 519 } else { 520 dir += ENTRIES_PER_PAGE/2; 521 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 522 while (stage <= idx) 523 stage += ENTRIES_PER_PAGEPAGE; 524 middir = *dir; 525 if (*dir) { 526 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 527 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 528 if (!diroff && !offset) { 529 *dir = NULL; 530 nr_pages_to_free++; 531 list_add(&middir->lru, &pages_to_free); 532 } 533 shmem_dir_unmap(dir); 534 dir = shmem_dir_map(middir); 535 } else { 536 diroff = 0; 537 offset = 0; 538 idx = stage; 539 } 540 } 541 542 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 543 if (unlikely(idx == stage)) { 544 shmem_dir_unmap(dir); 545 dir = shmem_dir_map(topdir) + 546 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 547 while (!*dir) { 548 dir++; 549 idx += ENTRIES_PER_PAGEPAGE; 550 if (idx >= limit) 551 goto done1; 552 } 553 stage = idx + ENTRIES_PER_PAGEPAGE; 554 middir = *dir; 555 *dir = NULL; 556 nr_pages_to_free++; 557 list_add(&middir->lru, &pages_to_free); 558 shmem_dir_unmap(dir); 559 cond_resched(); 560 dir = shmem_dir_map(middir); 561 diroff = 0; 562 } 563 subdir = dir[diroff]; 564 if (subdir && subdir->nr_swapped) { 565 size = limit - idx; 566 if (size > ENTRIES_PER_PAGE) 567 size = ENTRIES_PER_PAGE; 568 freed = shmem_map_and_free_swp(subdir, 569 offset, size, &dir); 570 if (!dir) 571 dir = shmem_dir_map(middir); 572 nr_swaps_freed += freed; 573 if (offset) 574 spin_lock(&info->lock); 575 subdir->nr_swapped -= freed; 576 if (offset) 577 spin_unlock(&info->lock); 578 BUG_ON(subdir->nr_swapped > offset); 579 } 580 if (offset) 581 offset = 0; 582 else if (subdir) { 583 dir[diroff] = NULL; 584 nr_pages_to_free++; 585 list_add(&subdir->lru, &pages_to_free); 586 } 587 } 588done1: 589 shmem_dir_unmap(dir); 590done2: 591 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 592 /* 593 * Call truncate_inode_pages again: racing shmem_unuse_inode 594 * may have swizzled a page in from swap since vmtruncate or 595 * generic_delete_inode did it, before we lowered next_index. 596 * Also, though shmem_getpage checks i_size before adding to 597 * cache, no recheck after: so fix the narrow window there too. 598 */ 599 truncate_inode_pages(inode->i_mapping, inode->i_size); 600 } 601 602 spin_lock(&info->lock); 603 info->flags &= ~SHMEM_TRUNCATE; 604 info->swapped -= nr_swaps_freed; 605 if (nr_pages_to_free) 606 shmem_free_blocks(inode, nr_pages_to_free); 607 shmem_recalc_inode(inode); 608 spin_unlock(&info->lock); 609 610 /* 611 * Empty swap vector directory pages to be freed? 612 */ 613 if (!list_empty(&pages_to_free)) { 614 pages_to_free.prev->next = NULL; 615 shmem_free_pages(pages_to_free.next); 616 } 617} 618 619static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 620{ 621 struct inode *inode = dentry->d_inode; 622 struct page *page = NULL; 623 int error; 624 625 if (attr->ia_valid & ATTR_SIZE) { 626 if (attr->ia_size < inode->i_size) { 627 /* 628 * If truncating down to a partial page, then 629 * if that page is already allocated, hold it 630 * in memory until the truncation is over, so 631 * truncate_partial_page cannnot miss it were 632 * it assigned to swap. 633 */ 634 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { 635 (void) shmem_getpage(inode, 636 attr->ia_size>>PAGE_CACHE_SHIFT, 637 &page, SGP_READ, NULL); 638 } 639 /* 640 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 641 * detect if any pages might have been added to cache 642 * after truncate_inode_pages. But we needn't bother 643 * if it's being fully truncated to zero-length: the 644 * nrpages check is efficient enough in that case. 645 */ 646 if (attr->ia_size) { 647 struct shmem_inode_info *info = SHMEM_I(inode); 648 spin_lock(&info->lock); 649 info->flags &= ~SHMEM_PAGEIN; 650 spin_unlock(&info->lock); 651 } 652 } 653 } 654 655 error = inode_change_ok(inode, attr); 656 if (!error) 657 error = inode_setattr(inode, attr); 658 if (page) 659 page_cache_release(page); 660 return error; 661} 662 663static void shmem_delete_inode(struct inode *inode) 664{ 665 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 666 struct shmem_inode_info *info = SHMEM_I(inode); 667 668 if (inode->i_op->truncate == shmem_truncate) { 669 truncate_inode_pages(inode->i_mapping, 0); 670 shmem_unacct_size(info->flags, inode->i_size); 671 inode->i_size = 0; 672 shmem_truncate(inode); 673 if (!list_empty(&info->swaplist)) { 674 spin_lock(&shmem_swaplist_lock); 675 list_del_init(&info->swaplist); 676 spin_unlock(&shmem_swaplist_lock); 677 } 678 } 679 BUG_ON(inode->i_blocks); 680 if (sbinfo->max_inodes) { 681 spin_lock(&sbinfo->stat_lock); 682 sbinfo->free_inodes++; 683 spin_unlock(&sbinfo->stat_lock); 684 } 685 clear_inode(inode); 686} 687 688static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 689{ 690 swp_entry_t *ptr; 691 692 for (ptr = dir; ptr < edir; ptr++) { 693 if (ptr->val == entry.val) 694 return ptr - dir; 695 } 696 return -1; 697} 698 699static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 700{ 701 struct inode *inode; 702 unsigned long idx; 703 unsigned long size; 704 unsigned long limit; 705 unsigned long stage; 706 struct page **dir; 707 struct page *subdir; 708 swp_entry_t *ptr; 709 int offset; 710 711 idx = 0; 712 ptr = info->i_direct; 713 spin_lock(&info->lock); 714 limit = info->next_index; 715 size = limit; 716 if (size > SHMEM_NR_DIRECT) 717 size = SHMEM_NR_DIRECT; 718 offset = shmem_find_swp(entry, ptr, ptr+size); 719 if (offset >= 0) { 720 shmem_swp_balance_unmap(); 721 goto found; 722 } 723 if (!info->i_indirect) 724 goto lost2; 725 726 dir = shmem_dir_map(info->i_indirect); 727 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 728 729 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 730 if (unlikely(idx == stage)) { 731 shmem_dir_unmap(dir-1); 732 dir = shmem_dir_map(info->i_indirect) + 733 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 734 while (!*dir) { 735 dir++; 736 idx += ENTRIES_PER_PAGEPAGE; 737 if (idx >= limit) 738 goto lost1; 739 } 740 stage = idx + ENTRIES_PER_PAGEPAGE; 741 subdir = *dir; 742 shmem_dir_unmap(dir); 743 dir = shmem_dir_map(subdir); 744 } 745 subdir = *dir; 746 if (subdir && subdir->nr_swapped) { 747 ptr = shmem_swp_map(subdir); 748 size = limit - idx; 749 if (size > ENTRIES_PER_PAGE) 750 size = ENTRIES_PER_PAGE; 751 offset = shmem_find_swp(entry, ptr, ptr+size); 752 if (offset >= 0) { 753 shmem_dir_unmap(dir); 754 goto found; 755 } 756 shmem_swp_unmap(ptr); 757 } 758 } 759lost1: 760 shmem_dir_unmap(dir-1); 761lost2: 762 spin_unlock(&info->lock); 763 return 0; 764found: 765 idx += offset; 766 inode = &info->vfs_inode; 767 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) { 768 info->flags |= SHMEM_PAGEIN; 769 shmem_swp_set(info, ptr + offset, 0); 770 } 771 shmem_swp_unmap(ptr); 772 spin_unlock(&info->lock); 773 /* 774 * Decrement swap count even when the entry is left behind: 775 * try_to_unuse will skip over mms, then reincrement count. 776 */ 777 swap_free(entry); 778 return 1; 779} 780 781/* 782 * shmem_unuse() search for an eventually swapped out shmem page. 783 */ 784int shmem_unuse(swp_entry_t entry, struct page *page) 785{ 786 struct list_head *p, *next; 787 struct shmem_inode_info *info; 788 int found = 0; 789 790 spin_lock(&shmem_swaplist_lock); 791 list_for_each_safe(p, next, &shmem_swaplist) { 792 info = list_entry(p, struct shmem_inode_info, swaplist); 793 if (!info->swapped) 794 list_del_init(&info->swaplist); 795 else if (shmem_unuse_inode(info, entry, page)) { 796 /* move head to start search for next from here */ 797 list_move_tail(&shmem_swaplist, &info->swaplist); 798 found = 1; 799 break; 800 } 801 } 802 spin_unlock(&shmem_swaplist_lock); 803 return found; 804} 805 806/* 807 * Move the page from the page cache to the swap cache. 808 */ 809static int shmem_writepage(struct page *page, struct writeback_control *wbc) 810{ 811 struct shmem_inode_info *info; 812 swp_entry_t *entry, swap; 813 struct address_space *mapping; 814 unsigned long index; 815 struct inode *inode; 816 817 BUG_ON(!PageLocked(page)); 818 BUG_ON(page_mapped(page)); 819 820 mapping = page->mapping; 821 index = page->index; 822 inode = mapping->host; 823 info = SHMEM_I(inode); 824 if (info->flags & VM_LOCKED) 825 goto redirty; 826 swap = get_swap_page(); 827 if (!swap.val) 828 goto redirty; 829 830 spin_lock(&info->lock); 831 shmem_recalc_inode(inode); 832 if (index >= info->next_index) { 833 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 834 goto unlock; 835 } 836 entry = shmem_swp_entry(info, index, NULL); 837 BUG_ON(!entry); 838 BUG_ON(entry->val); 839 840 if (move_to_swap_cache(page, swap) == 0) { 841 shmem_swp_set(info, entry, swap.val); 842 shmem_swp_unmap(entry); 843 spin_unlock(&info->lock); 844 if (list_empty(&info->swaplist)) { 845 spin_lock(&shmem_swaplist_lock); 846 /* move instead of add in case we're racing */ 847 list_move_tail(&info->swaplist, &shmem_swaplist); 848 spin_unlock(&shmem_swaplist_lock); 849 } 850 unlock_page(page); 851 return 0; 852 } 853 854 shmem_swp_unmap(entry); 855unlock: 856 spin_unlock(&info->lock); 857 swap_free(swap); 858redirty: 859 set_page_dirty(page); 860 return WRITEPAGE_ACTIVATE; /* Return with the page locked */ 861} 862 863#ifdef CONFIG_NUMA 864static struct page *shmem_swapin_async(struct shared_policy *p, 865 swp_entry_t entry, unsigned long idx) 866{ 867 struct page *page; 868 struct vm_area_struct pvma; 869 870 /* Create a pseudo vma that just contains the policy */ 871 memset(&pvma, 0, sizeof(struct vm_area_struct)); 872 pvma.vm_end = PAGE_SIZE; 873 pvma.vm_pgoff = idx; 874 pvma.vm_policy = mpol_shared_policy_lookup(p, idx); 875 page = read_swap_cache_async(entry, &pvma, 0); 876 mpol_free(pvma.vm_policy); 877 return page; 878} 879 880struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry, 881 unsigned long idx) 882{ 883 struct shared_policy *p = &info->policy; 884 int i, num; 885 struct page *page; 886 unsigned long offset; 887 888 num = valid_swaphandles(entry, &offset); 889 for (i = 0; i < num; offset++, i++) { 890 page = shmem_swapin_async(p, 891 swp_entry(swp_type(entry), offset), idx); 892 if (!page) 893 break; 894 page_cache_release(page); 895 } 896 lru_add_drain(); /* Push any new pages onto the LRU now */ 897 return shmem_swapin_async(p, entry, idx); 898} 899 900static struct page * 901shmem_alloc_page(unsigned long gfp, struct shmem_inode_info *info, 902 unsigned long idx) 903{ 904 struct vm_area_struct pvma; 905 struct page *page; 906 907 memset(&pvma, 0, sizeof(struct vm_area_struct)); 908 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 909 pvma.vm_pgoff = idx; 910 pvma.vm_end = PAGE_SIZE; 911 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0); 912 mpol_free(pvma.vm_policy); 913 return page; 914} 915#else 916static inline struct page * 917shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx) 918{ 919 swapin_readahead(entry, 0, NULL); 920 return read_swap_cache_async(entry, NULL, 0); 921} 922 923static inline struct page * 924shmem_alloc_page(unsigned int __nocast gfp,struct shmem_inode_info *info, 925 unsigned long idx) 926{ 927 return alloc_page(gfp | __GFP_ZERO); 928} 929#endif 930 931/* 932 * shmem_getpage - either get the page from swap or allocate a new one 933 * 934 * If we allocate a new one we do not mark it dirty. That's up to the 935 * vm. If we swap it in we mark it dirty since we also free the swap 936 * entry since a page cannot live in both the swap and page cache 937 */ 938static int shmem_getpage(struct inode *inode, unsigned long idx, 939 struct page **pagep, enum sgp_type sgp, int *type) 940{ 941 struct address_space *mapping = inode->i_mapping; 942 struct shmem_inode_info *info = SHMEM_I(inode); 943 struct shmem_sb_info *sbinfo; 944 struct page *filepage = *pagep; 945 struct page *swappage; 946 swp_entry_t *entry; 947 swp_entry_t swap; 948 int error; 949 950 if (idx >= SHMEM_MAX_INDEX) 951 return -EFBIG; 952 /* 953 * Normally, filepage is NULL on entry, and either found 954 * uptodate immediately, or allocated and zeroed, or read 955 * in under swappage, which is then assigned to filepage. 956 * But shmem_prepare_write passes in a locked filepage, 957 * which may be found not uptodate by other callers too, 958 * and may need to be copied from the swappage read in. 959 */ 960repeat: 961 if (!filepage) 962 filepage = find_lock_page(mapping, idx); 963 if (filepage && PageUptodate(filepage)) 964 goto done; 965 error = 0; 966 if (sgp == SGP_QUICK) 967 goto failed; 968 969 spin_lock(&info->lock); 970 shmem_recalc_inode(inode); 971 entry = shmem_swp_alloc(info, idx, sgp); 972 if (IS_ERR(entry)) { 973 spin_unlock(&info->lock); 974 error = PTR_ERR(entry); 975 goto failed; 976 } 977 swap = *entry; 978 979 if (swap.val) { 980 /* Look it up and read it in.. */ 981 swappage = lookup_swap_cache(swap); 982 if (!swappage) { 983 shmem_swp_unmap(entry); 984 spin_unlock(&info->lock); 985 /* here we actually do the io */ 986 if (type && *type == VM_FAULT_MINOR) { 987 inc_page_state(pgmajfault); 988 *type = VM_FAULT_MAJOR; 989 } 990 swappage = shmem_swapin(info, swap, idx); 991 if (!swappage) { 992 spin_lock(&info->lock); 993 entry = shmem_swp_alloc(info, idx, sgp); 994 if (IS_ERR(entry)) 995 error = PTR_ERR(entry); 996 else { 997 if (entry->val == swap.val) 998 error = -ENOMEM; 999 shmem_swp_unmap(entry); 1000 } 1001 spin_unlock(&info->lock); 1002 if (error) 1003 goto failed; 1004 goto repeat; 1005 } 1006 wait_on_page_locked(swappage); 1007 page_cache_release(swappage); 1008 goto repeat; 1009 } 1010 1011 /* We have to do this with page locked to prevent races */ 1012 if (TestSetPageLocked(swappage)) { 1013 shmem_swp_unmap(entry); 1014 spin_unlock(&info->lock); 1015 wait_on_page_locked(swappage); 1016 page_cache_release(swappage); 1017 goto repeat; 1018 } 1019 if (PageWriteback(swappage)) { 1020 shmem_swp_unmap(entry); 1021 spin_unlock(&info->lock); 1022 wait_on_page_writeback(swappage); 1023 unlock_page(swappage); 1024 page_cache_release(swappage); 1025 goto repeat; 1026 } 1027 if (!PageUptodate(swappage)) { 1028 shmem_swp_unmap(entry); 1029 spin_unlock(&info->lock); 1030 unlock_page(swappage); 1031 page_cache_release(swappage); 1032 error = -EIO; 1033 goto failed; 1034 } 1035 1036 if (filepage) { 1037 shmem_swp_set(info, entry, 0); 1038 shmem_swp_unmap(entry); 1039 delete_from_swap_cache(swappage); 1040 spin_unlock(&info->lock); 1041 copy_highpage(filepage, swappage); 1042 unlock_page(swappage); 1043 page_cache_release(swappage); 1044 flush_dcache_page(filepage); 1045 SetPageUptodate(filepage); 1046 set_page_dirty(filepage); 1047 swap_free(swap); 1048 } else if (!(error = move_from_swap_cache( 1049 swappage, idx, mapping))) { 1050 info->flags |= SHMEM_PAGEIN; 1051 shmem_swp_set(info, entry, 0); 1052 shmem_swp_unmap(entry); 1053 spin_unlock(&info->lock); 1054 filepage = swappage; 1055 swap_free(swap); 1056 } else { 1057 shmem_swp_unmap(entry); 1058 spin_unlock(&info->lock); 1059 unlock_page(swappage); 1060 page_cache_release(swappage); 1061 if (error == -ENOMEM) { 1062 /* let kswapd refresh zone for GFP_ATOMICs */ 1063 blk_congestion_wait(WRITE, HZ/50); 1064 } 1065 goto repeat; 1066 } 1067 } else if (sgp == SGP_READ && !filepage) { 1068 shmem_swp_unmap(entry); 1069 filepage = find_get_page(mapping, idx); 1070 if (filepage && 1071 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1072 spin_unlock(&info->lock); 1073 wait_on_page_locked(filepage); 1074 page_cache_release(filepage); 1075 filepage = NULL; 1076 goto repeat; 1077 } 1078 spin_unlock(&info->lock); 1079 } else { 1080 shmem_swp_unmap(entry); 1081 sbinfo = SHMEM_SB(inode->i_sb); 1082 if (sbinfo->max_blocks) { 1083 spin_lock(&sbinfo->stat_lock); 1084 if (sbinfo->free_blocks == 0 || 1085 shmem_acct_block(info->flags)) { 1086 spin_unlock(&sbinfo->stat_lock); 1087 spin_unlock(&info->lock); 1088 error = -ENOSPC; 1089 goto failed; 1090 } 1091 sbinfo->free_blocks--; 1092 inode->i_blocks += BLOCKS_PER_PAGE; 1093 spin_unlock(&sbinfo->stat_lock); 1094 } else if (shmem_acct_block(info->flags)) { 1095 spin_unlock(&info->lock); 1096 error = -ENOSPC; 1097 goto failed; 1098 } 1099 1100 if (!filepage) { 1101 spin_unlock(&info->lock); 1102 filepage = shmem_alloc_page(mapping_gfp_mask(mapping), 1103 info, 1104 idx); 1105 if (!filepage) { 1106 shmem_unacct_blocks(info->flags, 1); 1107 shmem_free_blocks(inode, 1); 1108 error = -ENOMEM; 1109 goto failed; 1110 } 1111 1112 spin_lock(&info->lock); 1113 entry = shmem_swp_alloc(info, idx, sgp); 1114 if (IS_ERR(entry)) 1115 error = PTR_ERR(entry); 1116 else { 1117 swap = *entry; 1118 shmem_swp_unmap(entry); 1119 } 1120 if (error || swap.val || 0 != add_to_page_cache_lru( 1121 filepage, mapping, idx, GFP_ATOMIC)) { 1122 spin_unlock(&info->lock); 1123 page_cache_release(filepage); 1124 shmem_unacct_blocks(info->flags, 1); 1125 shmem_free_blocks(inode, 1); 1126 filepage = NULL; 1127 if (error) 1128 goto failed; 1129 goto repeat; 1130 } 1131 info->flags |= SHMEM_PAGEIN; 1132 } 1133 1134 info->alloced++; 1135 spin_unlock(&info->lock); 1136 flush_dcache_page(filepage); 1137 SetPageUptodate(filepage); 1138 } 1139done: 1140 if (*pagep != filepage) { 1141 unlock_page(filepage); 1142 *pagep = filepage; 1143 } 1144 return 0; 1145 1146failed: 1147 if (*pagep != filepage) { 1148 unlock_page(filepage); 1149 page_cache_release(filepage); 1150 } 1151 return error; 1152} 1153 1154struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type) 1155{ 1156 struct inode *inode = vma->vm_file->f_dentry->d_inode; 1157 struct page *page = NULL; 1158 unsigned long idx; 1159 int error; 1160 1161 idx = (address - vma->vm_start) >> PAGE_SHIFT; 1162 idx += vma->vm_pgoff; 1163 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT; 1164 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1165 return NOPAGE_SIGBUS; 1166 1167 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type); 1168 if (error) 1169 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS; 1170 1171 mark_page_accessed(page); 1172 return page; 1173} 1174 1175static int shmem_populate(struct vm_area_struct *vma, 1176 unsigned long addr, unsigned long len, 1177 pgprot_t prot, unsigned long pgoff, int nonblock) 1178{ 1179 struct inode *inode = vma->vm_file->f_dentry->d_inode; 1180 struct mm_struct *mm = vma->vm_mm; 1181 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE; 1182 unsigned long size; 1183 1184 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; 1185 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size) 1186 return -EINVAL; 1187 1188 while ((long) len > 0) { 1189 struct page *page = NULL; 1190 int err; 1191 /* 1192 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE 1193 */ 1194 err = shmem_getpage(inode, pgoff, &page, sgp, NULL); 1195 if (err) 1196 return err; 1197 /* Page may still be null, but only if nonblock was set. */ 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 { 1206 /* No page was found just because we can't read it in 1207 * now (being here implies nonblock != 0), but the page 1208 * may exist, so set the PTE to fault it in later. */ 1209 err = install_file_pte(mm, vma, addr, pgoff, prot); 1210 if (err) 1211 return err; 1212 } 1213 1214 len -= PAGE_SIZE; 1215 addr += PAGE_SIZE; 1216 pgoff++; 1217 } 1218 return 0; 1219} 1220 1221#ifdef CONFIG_NUMA 1222int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1223{ 1224 struct inode *i = vma->vm_file->f_dentry->d_inode; 1225 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1226} 1227 1228struct mempolicy * 1229shmem_get_policy(struct vm_area_struct *vma, unsigned long addr) 1230{ 1231 struct inode *i = vma->vm_file->f_dentry->d_inode; 1232 unsigned long idx; 1233 1234 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1235 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1236} 1237#endif 1238 1239int shmem_lock(struct file *file, int lock, struct user_struct *user) 1240{ 1241 struct inode *inode = file->f_dentry->d_inode; 1242 struct shmem_inode_info *info = SHMEM_I(inode); 1243 int retval = -ENOMEM; 1244 1245 spin_lock(&info->lock); 1246 if (lock && !(info->flags & VM_LOCKED)) { 1247 if (!user_shm_lock(inode->i_size, user)) 1248 goto out_nomem; 1249 info->flags |= VM_LOCKED; 1250 } 1251 if (!lock && (info->flags & VM_LOCKED) && user) { 1252 user_shm_unlock(inode->i_size, user); 1253 info->flags &= ~VM_LOCKED; 1254 } 1255 retval = 0; 1256out_nomem: 1257 spin_unlock(&info->lock); 1258 return retval; 1259} 1260 1261static int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1262{ 1263 file_accessed(file); 1264 vma->vm_ops = &shmem_vm_ops; 1265 return 0; 1266} 1267 1268static struct inode * 1269shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1270{ 1271 struct inode *inode; 1272 struct shmem_inode_info *info; 1273 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1274 1275 if (sbinfo->max_inodes) { 1276 spin_lock(&sbinfo->stat_lock); 1277 if (!sbinfo->free_inodes) { 1278 spin_unlock(&sbinfo->stat_lock); 1279 return NULL; 1280 } 1281 sbinfo->free_inodes--; 1282 spin_unlock(&sbinfo->stat_lock); 1283 } 1284 1285 inode = new_inode(sb); 1286 if (inode) { 1287 inode->i_mode = mode; 1288 inode->i_uid = current->fsuid; 1289 inode->i_gid = current->fsgid; 1290 inode->i_blksize = PAGE_CACHE_SIZE; 1291 inode->i_blocks = 0; 1292 inode->i_mapping->a_ops = &shmem_aops; 1293 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1294 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1295 info = SHMEM_I(inode); 1296 memset(info, 0, (char *)inode - (char *)info); 1297 spin_lock_init(&info->lock); 1298 INIT_LIST_HEAD(&info->swaplist); 1299 1300 switch (mode & S_IFMT) { 1301 default: 1302 init_special_inode(inode, mode, dev); 1303 break; 1304 case S_IFREG: 1305 inode->i_op = &shmem_inode_operations; 1306 inode->i_fop = &shmem_file_operations; 1307 mpol_shared_policy_init(&info->policy); 1308 break; 1309 case S_IFDIR: 1310 inode->i_nlink++; 1311 /* Some things misbehave if size == 0 on a directory */ 1312 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1313 inode->i_op = &shmem_dir_inode_operations; 1314 inode->i_fop = &simple_dir_operations; 1315 break; 1316 case S_IFLNK: 1317 /* 1318 * Must not load anything in the rbtree, 1319 * mpol_free_shared_policy will not be called. 1320 */ 1321 mpol_shared_policy_init(&info->policy); 1322 break; 1323 } 1324 } else if (sbinfo->max_inodes) { 1325 spin_lock(&sbinfo->stat_lock); 1326 sbinfo->free_inodes++; 1327 spin_unlock(&sbinfo->stat_lock); 1328 } 1329 return inode; 1330} 1331 1332#ifdef CONFIG_TMPFS 1333static struct inode_operations shmem_symlink_inode_operations; 1334static struct inode_operations shmem_symlink_inline_operations; 1335 1336/* 1337 * Normally tmpfs makes no use of shmem_prepare_write, but it 1338 * lets a tmpfs file be used read-write below the loop driver. 1339 */ 1340static int 1341shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to) 1342{ 1343 struct inode *inode = page->mapping->host; 1344 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL); 1345} 1346 1347static ssize_t 1348shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 1349{ 1350 struct inode *inode = file->f_dentry->d_inode; 1351 loff_t pos; 1352 unsigned long written; 1353 ssize_t err; 1354 1355 if ((ssize_t) count < 0) 1356 return -EINVAL; 1357 1358 if (!access_ok(VERIFY_READ, buf, count)) 1359 return -EFAULT; 1360 1361 down(&inode->i_sem); 1362 1363 pos = *ppos; 1364 written = 0; 1365 1366 err = generic_write_checks(file, &pos, &count, 0); 1367 if (err || !count) 1368 goto out; 1369 1370 err = remove_suid(file->f_dentry); 1371 if (err) 1372 goto out; 1373 1374 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 1375 1376 do { 1377 struct page *page = NULL; 1378 unsigned long bytes, index, offset; 1379 char *kaddr; 1380 int left; 1381 1382 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1383 index = pos >> PAGE_CACHE_SHIFT; 1384 bytes = PAGE_CACHE_SIZE - offset; 1385 if (bytes > count) 1386 bytes = count; 1387 1388 /* 1389 * We don't hold page lock across copy from user - 1390 * what would it guard against? - so no deadlock here. 1391 * But it still may be a good idea to prefault below. 1392 */ 1393 1394 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL); 1395 if (err) 1396 break; 1397 1398 left = bytes; 1399 if (PageHighMem(page)) { 1400 volatile unsigned char dummy; 1401 __get_user(dummy, buf); 1402 __get_user(dummy, buf + bytes - 1); 1403 1404 kaddr = kmap_atomic(page, KM_USER0); 1405 left = __copy_from_user_inatomic(kaddr + offset, 1406 buf, bytes); 1407 kunmap_atomic(kaddr, KM_USER0); 1408 } 1409 if (left) { 1410 kaddr = kmap(page); 1411 left = __copy_from_user(kaddr + offset, buf, bytes); 1412 kunmap(page); 1413 } 1414 1415 written += bytes; 1416 count -= bytes; 1417 pos += bytes; 1418 buf += bytes; 1419 if (pos > inode->i_size) 1420 i_size_write(inode, pos); 1421 1422 flush_dcache_page(page); 1423 set_page_dirty(page); 1424 mark_page_accessed(page); 1425 page_cache_release(page); 1426 1427 if (left) { 1428 pos -= left; 1429 written -= left; 1430 err = -EFAULT; 1431 break; 1432 } 1433 1434 /* 1435 * Our dirty pages are not counted in nr_dirty, 1436 * and we do not attempt to balance dirty pages. 1437 */ 1438 1439 cond_resched(); 1440 } while (count); 1441 1442 *ppos = pos; 1443 if (written) 1444 err = written; 1445out: 1446 up(&inode->i_sem); 1447 return err; 1448} 1449 1450static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1451{ 1452 struct inode *inode = filp->f_dentry->d_inode; 1453 struct address_space *mapping = inode->i_mapping; 1454 unsigned long index, offset; 1455 1456 index = *ppos >> PAGE_CACHE_SHIFT; 1457 offset = *ppos & ~PAGE_CACHE_MASK; 1458 1459 for (;;) { 1460 struct page *page = NULL; 1461 unsigned long end_index, nr, ret; 1462 loff_t i_size = i_size_read(inode); 1463 1464 end_index = i_size >> PAGE_CACHE_SHIFT; 1465 if (index > end_index) 1466 break; 1467 if (index == end_index) { 1468 nr = i_size & ~PAGE_CACHE_MASK; 1469 if (nr <= offset) 1470 break; 1471 } 1472 1473 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL); 1474 if (desc->error) { 1475 if (desc->error == -EINVAL) 1476 desc->error = 0; 1477 break; 1478 } 1479 1480 /* 1481 * We must evaluate after, since reads (unlike writes) 1482 * are called without i_sem protection against truncate 1483 */ 1484 nr = PAGE_CACHE_SIZE; 1485 i_size = i_size_read(inode); 1486 end_index = i_size >> PAGE_CACHE_SHIFT; 1487 if (index == end_index) { 1488 nr = i_size & ~PAGE_CACHE_MASK; 1489 if (nr <= offset) { 1490 if (page) 1491 page_cache_release(page); 1492 break; 1493 } 1494 } 1495 nr -= offset; 1496 1497 if (page) { 1498 /* 1499 * If users can be writing to this page using arbitrary 1500 * virtual addresses, take care about potential aliasing 1501 * before reading the page on the kernel side. 1502 */ 1503 if (mapping_writably_mapped(mapping)) 1504 flush_dcache_page(page); 1505 /* 1506 * Mark the page accessed if we read the beginning. 1507 */ 1508 if (!offset) 1509 mark_page_accessed(page); 1510 } else 1511 page = ZERO_PAGE(0); 1512 1513 /* 1514 * Ok, we have the page, and it's up-to-date, so 1515 * now we can copy it to user space... 1516 * 1517 * The actor routine returns how many bytes were actually used.. 1518 * NOTE! This may not be the same as how much of a user buffer 1519 * we filled up (we may be padding etc), so we can only update 1520 * "pos" here (the actor routine has to update the user buffer 1521 * pointers and the remaining count). 1522 */ 1523 ret = actor(desc, page, offset, nr); 1524 offset += ret; 1525 index += offset >> PAGE_CACHE_SHIFT; 1526 offset &= ~PAGE_CACHE_MASK; 1527 1528 page_cache_release(page); 1529 if (ret != nr || !desc->count) 1530 break; 1531 1532 cond_resched(); 1533 } 1534 1535 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1536 file_accessed(filp); 1537} 1538 1539static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1540{ 1541 read_descriptor_t desc; 1542 1543 if ((ssize_t) count < 0) 1544 return -EINVAL; 1545 if (!access_ok(VERIFY_WRITE, buf, count)) 1546 return -EFAULT; 1547 if (!count) 1548 return 0; 1549 1550 desc.written = 0; 1551 desc.count = count; 1552 desc.arg.buf = buf; 1553 desc.error = 0; 1554 1555 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1556 if (desc.written) 1557 return desc.written; 1558 return desc.error; 1559} 1560 1561static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos, 1562 size_t count, read_actor_t actor, void *target) 1563{ 1564 read_descriptor_t desc; 1565 1566 if (!count) 1567 return 0; 1568 1569 desc.written = 0; 1570 desc.count = count; 1571 desc.arg.data = target; 1572 desc.error = 0; 1573 1574 do_shmem_file_read(in_file, ppos, &desc, actor); 1575 if (desc.written) 1576 return desc.written; 1577 return desc.error; 1578} 1579 1580static int shmem_statfs(struct super_block *sb, struct kstatfs *buf) 1581{ 1582 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1583 1584 buf->f_type = TMPFS_MAGIC; 1585 buf->f_bsize = PAGE_CACHE_SIZE; 1586 buf->f_namelen = NAME_MAX; 1587 spin_lock(&sbinfo->stat_lock); 1588 if (sbinfo->max_blocks) { 1589 buf->f_blocks = sbinfo->max_blocks; 1590 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1591 } 1592 if (sbinfo->max_inodes) { 1593 buf->f_files = sbinfo->max_inodes; 1594 buf->f_ffree = sbinfo->free_inodes; 1595 } 1596 /* else leave those fields 0 like simple_statfs */ 1597 spin_unlock(&sbinfo->stat_lock); 1598 return 0; 1599} 1600 1601/* 1602 * File creation. Allocate an inode, and we're done.. 1603 */ 1604static int 1605shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1606{ 1607 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1608 int error = -ENOSPC; 1609 1610 if (inode) { 1611 if (dir->i_mode & S_ISGID) { 1612 inode->i_gid = dir->i_gid; 1613 if (S_ISDIR(mode)) 1614 inode->i_mode |= S_ISGID; 1615 } 1616 dir->i_size += BOGO_DIRENT_SIZE; 1617 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1618 d_instantiate(dentry, inode); 1619 dget(dentry); /* Extra count - pin the dentry in core */ 1620 error = 0; 1621 } 1622 return error; 1623} 1624 1625static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1626{ 1627 int error; 1628 1629 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1630 return error; 1631 dir->i_nlink++; 1632 return 0; 1633} 1634 1635static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1636 struct nameidata *nd) 1637{ 1638 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1639} 1640 1641/* 1642 * Link a file.. 1643 */ 1644static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1645{ 1646 struct inode *inode = old_dentry->d_inode; 1647 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1648 1649 /* 1650 * No ordinary (disk based) filesystem counts links as inodes; 1651 * but each new link needs a new dentry, pinning lowmem, and 1652 * tmpfs dentries cannot be pruned until they are unlinked. 1653 */ 1654 if (sbinfo->max_inodes) { 1655 spin_lock(&sbinfo->stat_lock); 1656 if (!sbinfo->free_inodes) { 1657 spin_unlock(&sbinfo->stat_lock); 1658 return -ENOSPC; 1659 } 1660 sbinfo->free_inodes--; 1661 spin_unlock(&sbinfo->stat_lock); 1662 } 1663 1664 dir->i_size += BOGO_DIRENT_SIZE; 1665 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1666 inode->i_nlink++; 1667 atomic_inc(&inode->i_count); /* New dentry reference */ 1668 dget(dentry); /* Extra pinning count for the created dentry */ 1669 d_instantiate(dentry, inode); 1670 return 0; 1671} 1672 1673static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1674{ 1675 struct inode *inode = dentry->d_inode; 1676 1677 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) { 1678 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1679 if (sbinfo->max_inodes) { 1680 spin_lock(&sbinfo->stat_lock); 1681 sbinfo->free_inodes++; 1682 spin_unlock(&sbinfo->stat_lock); 1683 } 1684 } 1685 1686 dir->i_size -= BOGO_DIRENT_SIZE; 1687 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1688 inode->i_nlink--; 1689 dput(dentry); /* Undo the count from "create" - this does all the work */ 1690 return 0; 1691} 1692 1693static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1694{ 1695 if (!simple_empty(dentry)) 1696 return -ENOTEMPTY; 1697 1698 dir->i_nlink--; 1699 return shmem_unlink(dir, dentry); 1700} 1701 1702/* 1703 * The VFS layer already does all the dentry stuff for rename, 1704 * we just have to decrement the usage count for the target if 1705 * it exists so that the VFS layer correctly free's it when it 1706 * gets overwritten. 1707 */ 1708static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1709{ 1710 struct inode *inode = old_dentry->d_inode; 1711 int they_are_dirs = S_ISDIR(inode->i_mode); 1712 1713 if (!simple_empty(new_dentry)) 1714 return -ENOTEMPTY; 1715 1716 if (new_dentry->d_inode) { 1717 (void) shmem_unlink(new_dir, new_dentry); 1718 if (they_are_dirs) 1719 old_dir->i_nlink--; 1720 } else if (they_are_dirs) { 1721 old_dir->i_nlink--; 1722 new_dir->i_nlink++; 1723 } 1724 1725 old_dir->i_size -= BOGO_DIRENT_SIZE; 1726 new_dir->i_size += BOGO_DIRENT_SIZE; 1727 old_dir->i_ctime = old_dir->i_mtime = 1728 new_dir->i_ctime = new_dir->i_mtime = 1729 inode->i_ctime = CURRENT_TIME; 1730 return 0; 1731} 1732 1733static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1734{ 1735 int error; 1736 int len; 1737 struct inode *inode; 1738 struct page *page = NULL; 1739 char *kaddr; 1740 struct shmem_inode_info *info; 1741 1742 len = strlen(symname) + 1; 1743 if (len > PAGE_CACHE_SIZE) 1744 return -ENAMETOOLONG; 1745 1746 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1747 if (!inode) 1748 return -ENOSPC; 1749 1750 info = SHMEM_I(inode); 1751 inode->i_size = len-1; 1752 if (len <= (char *)inode - (char *)info) { 1753 /* do it inline */ 1754 memcpy(info, symname, len); 1755 inode->i_op = &shmem_symlink_inline_operations; 1756 } else { 1757 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1758 if (error) { 1759 iput(inode); 1760 return error; 1761 } 1762 inode->i_op = &shmem_symlink_inode_operations; 1763 kaddr = kmap_atomic(page, KM_USER0); 1764 memcpy(kaddr, symname, len); 1765 kunmap_atomic(kaddr, KM_USER0); 1766 set_page_dirty(page); 1767 page_cache_release(page); 1768 } 1769 if (dir->i_mode & S_ISGID) 1770 inode->i_gid = dir->i_gid; 1771 dir->i_size += BOGO_DIRENT_SIZE; 1772 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1773 d_instantiate(dentry, inode); 1774 dget(dentry); 1775 return 0; 1776} 1777 1778static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1779{ 1780 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1781 return NULL; 1782} 1783 1784static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1785{ 1786 struct page *page = NULL; 1787 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1788 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1789 return page; 1790} 1791 1792static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1793{ 1794 if (!IS_ERR(nd_get_link(nd))) { 1795 struct page *page = cookie; 1796 kunmap(page); 1797 mark_page_accessed(page); 1798 page_cache_release(page); 1799 } 1800} 1801 1802static struct inode_operations shmem_symlink_inline_operations = { 1803 .readlink = generic_readlink, 1804 .follow_link = shmem_follow_link_inline, 1805}; 1806 1807static struct inode_operations shmem_symlink_inode_operations = { 1808 .truncate = shmem_truncate, 1809 .readlink = generic_readlink, 1810 .follow_link = shmem_follow_link, 1811 .put_link = shmem_put_link, 1812}; 1813 1814static int shmem_parse_options(char *options, int *mode, uid_t *uid, gid_t *gid, unsigned long *blocks, unsigned long *inodes) 1815{ 1816 char *this_char, *value, *rest; 1817 1818 while ((this_char = strsep(&options, ",")) != NULL) { 1819 if (!*this_char) 1820 continue; 1821 if ((value = strchr(this_char,'=')) != NULL) { 1822 *value++ = 0; 1823 } else { 1824 printk(KERN_ERR 1825 "tmpfs: No value for mount option '%s'\n", 1826 this_char); 1827 return 1; 1828 } 1829 1830 if (!strcmp(this_char,"size")) { 1831 unsigned long long size; 1832 size = memparse(value,&rest); 1833 if (*rest == '%') { 1834 size <<= PAGE_SHIFT; 1835 size *= totalram_pages; 1836 do_div(size, 100); 1837 rest++; 1838 } 1839 if (*rest) 1840 goto bad_val; 1841 *blocks = size >> PAGE_CACHE_SHIFT; 1842 } else if (!strcmp(this_char,"nr_blocks")) { 1843 *blocks = memparse(value,&rest); 1844 if (*rest) 1845 goto bad_val; 1846 } else if (!strcmp(this_char,"nr_inodes")) { 1847 *inodes = memparse(value,&rest); 1848 if (*rest) 1849 goto bad_val; 1850 } else if (!strcmp(this_char,"mode")) { 1851 if (!mode) 1852 continue; 1853 *mode = simple_strtoul(value,&rest,8); 1854 if (*rest) 1855 goto bad_val; 1856 } else if (!strcmp(this_char,"uid")) { 1857 if (!uid) 1858 continue; 1859 *uid = simple_strtoul(value,&rest,0); 1860 if (*rest) 1861 goto bad_val; 1862 } else if (!strcmp(this_char,"gid")) { 1863 if (!gid) 1864 continue; 1865 *gid = simple_strtoul(value,&rest,0); 1866 if (*rest) 1867 goto bad_val; 1868 } else { 1869 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 1870 this_char); 1871 return 1; 1872 } 1873 } 1874 return 0; 1875 1876bad_val: 1877 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 1878 value, this_char); 1879 return 1; 1880 1881} 1882 1883static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 1884{ 1885 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1886 unsigned long max_blocks = sbinfo->max_blocks; 1887 unsigned long max_inodes = sbinfo->max_inodes; 1888 unsigned long blocks; 1889 unsigned long inodes; 1890 int error = -EINVAL; 1891 1892 if (shmem_parse_options(data, NULL, NULL, NULL, 1893 &max_blocks, &max_inodes)) 1894 return error; 1895 1896 spin_lock(&sbinfo->stat_lock); 1897 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 1898 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 1899 if (max_blocks < blocks) 1900 goto out; 1901 if (max_inodes < inodes) 1902 goto out; 1903 /* 1904 * Those tests also disallow limited->unlimited while any are in 1905 * use, so i_blocks will always be zero when max_blocks is zero; 1906 * but we must separately disallow unlimited->limited, because 1907 * in that case we have no record of how much is already in use. 1908 */ 1909 if (max_blocks && !sbinfo->max_blocks) 1910 goto out; 1911 if (max_inodes && !sbinfo->max_inodes) 1912 goto out; 1913 1914 error = 0; 1915 sbinfo->max_blocks = max_blocks; 1916 sbinfo->free_blocks = max_blocks - blocks; 1917 sbinfo->max_inodes = max_inodes; 1918 sbinfo->free_inodes = max_inodes - inodes; 1919out: 1920 spin_unlock(&sbinfo->stat_lock); 1921 return error; 1922} 1923#endif 1924 1925static void shmem_put_super(struct super_block *sb) 1926{ 1927 kfree(sb->s_fs_info); 1928 sb->s_fs_info = NULL; 1929} 1930 1931static int shmem_fill_super(struct super_block *sb, 1932 void *data, int silent) 1933{ 1934 struct inode *inode; 1935 struct dentry *root; 1936 int mode = S_IRWXUGO | S_ISVTX; 1937 uid_t uid = current->fsuid; 1938 gid_t gid = current->fsgid; 1939 int err = -ENOMEM; 1940 struct shmem_sb_info *sbinfo; 1941 unsigned long blocks = 0; 1942 unsigned long inodes = 0; 1943 1944#ifdef CONFIG_TMPFS 1945 /* 1946 * Per default we only allow half of the physical ram per 1947 * tmpfs instance, limiting inodes to one per page of lowmem; 1948 * but the internal instance is left unlimited. 1949 */ 1950 if (!(sb->s_flags & MS_NOUSER)) { 1951 blocks = totalram_pages / 2; 1952 inodes = totalram_pages - totalhigh_pages; 1953 if (inodes > blocks) 1954 inodes = blocks; 1955 if (shmem_parse_options(data, &mode, &uid, &gid, 1956 &blocks, &inodes)) 1957 return -EINVAL; 1958 } 1959#else 1960 sb->s_flags |= MS_NOUSER; 1961#endif 1962 1963 /* Round up to L1_CACHE_BYTES to resist false sharing */ 1964 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 1965 L1_CACHE_BYTES), GFP_KERNEL); 1966 if (!sbinfo) 1967 return -ENOMEM; 1968 1969 spin_lock_init(&sbinfo->stat_lock); 1970 sbinfo->max_blocks = blocks; 1971 sbinfo->free_blocks = blocks; 1972 sbinfo->max_inodes = inodes; 1973 sbinfo->free_inodes = inodes; 1974 1975 sb->s_fs_info = sbinfo; 1976 sb->s_maxbytes = SHMEM_MAX_BYTES; 1977 sb->s_blocksize = PAGE_CACHE_SIZE; 1978 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 1979 sb->s_magic = TMPFS_MAGIC; 1980 sb->s_op = &shmem_ops; 1981 1982 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 1983 if (!inode) 1984 goto failed; 1985 inode->i_uid = uid; 1986 inode->i_gid = gid; 1987 root = d_alloc_root(inode); 1988 if (!root) 1989 goto failed_iput; 1990 sb->s_root = root; 1991 return 0; 1992 1993failed_iput: 1994 iput(inode); 1995failed: 1996 shmem_put_super(sb); 1997 return err; 1998} 1999 2000static kmem_cache_t *shmem_inode_cachep; 2001 2002static struct inode *shmem_alloc_inode(struct super_block *sb) 2003{ 2004 struct shmem_inode_info *p; 2005 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL); 2006 if (!p) 2007 return NULL; 2008 return &p->vfs_inode; 2009} 2010 2011static void shmem_destroy_inode(struct inode *inode) 2012{ 2013 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2014 /* only struct inode is valid if it's an inline symlink */ 2015 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2016 } 2017 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2018} 2019 2020static void init_once(void *foo, kmem_cache_t *cachep, unsigned long flags) 2021{ 2022 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2023 2024 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == 2025 SLAB_CTOR_CONSTRUCTOR) { 2026 inode_init_once(&p->vfs_inode); 2027 } 2028} 2029 2030static int init_inodecache(void) 2031{ 2032 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2033 sizeof(struct shmem_inode_info), 2034 0, 0, init_once, NULL); 2035 if (shmem_inode_cachep == NULL) 2036 return -ENOMEM; 2037 return 0; 2038} 2039 2040static void destroy_inodecache(void) 2041{ 2042 if (kmem_cache_destroy(shmem_inode_cachep)) 2043 printk(KERN_INFO "shmem_inode_cache: not all structures were freed\n"); 2044} 2045 2046static struct address_space_operations shmem_aops = { 2047 .writepage = shmem_writepage, 2048 .set_page_dirty = __set_page_dirty_nobuffers, 2049#ifdef CONFIG_TMPFS 2050 .prepare_write = shmem_prepare_write, 2051 .commit_write = simple_commit_write, 2052#endif 2053}; 2054 2055static struct file_operations shmem_file_operations = { 2056 .mmap = shmem_mmap, 2057#ifdef CONFIG_TMPFS 2058 .llseek = generic_file_llseek, 2059 .read = shmem_file_read, 2060 .write = shmem_file_write, 2061 .fsync = simple_sync_file, 2062 .sendfile = shmem_file_sendfile, 2063#endif 2064}; 2065 2066static struct inode_operations shmem_inode_operations = { 2067 .truncate = shmem_truncate, 2068 .setattr = shmem_notify_change, 2069}; 2070 2071static struct inode_operations shmem_dir_inode_operations = { 2072#ifdef CONFIG_TMPFS 2073 .create = shmem_create, 2074 .lookup = simple_lookup, 2075 .link = shmem_link, 2076 .unlink = shmem_unlink, 2077 .symlink = shmem_symlink, 2078 .mkdir = shmem_mkdir, 2079 .rmdir = shmem_rmdir, 2080 .mknod = shmem_mknod, 2081 .rename = shmem_rename, 2082#endif 2083}; 2084 2085static struct super_operations shmem_ops = { 2086 .alloc_inode = shmem_alloc_inode, 2087 .destroy_inode = shmem_destroy_inode, 2088#ifdef CONFIG_TMPFS 2089 .statfs = shmem_statfs, 2090 .remount_fs = shmem_remount_fs, 2091#endif 2092 .delete_inode = shmem_delete_inode, 2093 .drop_inode = generic_delete_inode, 2094 .put_super = shmem_put_super, 2095}; 2096 2097static struct vm_operations_struct shmem_vm_ops = { 2098 .nopage = shmem_nopage, 2099 .populate = shmem_populate, 2100#ifdef CONFIG_NUMA 2101 .set_policy = shmem_set_policy, 2102 .get_policy = shmem_get_policy, 2103#endif 2104}; 2105 2106 2107static struct super_block *shmem_get_sb(struct file_system_type *fs_type, 2108 int flags, const char *dev_name, void *data) 2109{ 2110 return get_sb_nodev(fs_type, flags, data, shmem_fill_super); 2111} 2112 2113static struct file_system_type tmpfs_fs_type = { 2114 .owner = THIS_MODULE, 2115 .name = "tmpfs", 2116 .get_sb = shmem_get_sb, 2117 .kill_sb = kill_litter_super, 2118}; 2119static struct vfsmount *shm_mnt; 2120 2121static int __init init_tmpfs(void) 2122{ 2123 int error; 2124 2125 error = init_inodecache(); 2126 if (error) 2127 goto out3; 2128 2129 error = register_filesystem(&tmpfs_fs_type); 2130 if (error) { 2131 printk(KERN_ERR "Could not register tmpfs\n"); 2132 goto out2; 2133 } 2134#ifdef CONFIG_TMPFS 2135 devfs_mk_dir("shm"); 2136#endif 2137 shm_mnt = do_kern_mount(tmpfs_fs_type.name, MS_NOUSER, 2138 tmpfs_fs_type.name, NULL); 2139 if (IS_ERR(shm_mnt)) { 2140 error = PTR_ERR(shm_mnt); 2141 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2142 goto out1; 2143 } 2144 return 0; 2145 2146out1: 2147 unregister_filesystem(&tmpfs_fs_type); 2148out2: 2149 destroy_inodecache(); 2150out3: 2151 shm_mnt = ERR_PTR(error); 2152 return error; 2153} 2154module_init(init_tmpfs) 2155 2156/* 2157 * shmem_file_setup - get an unlinked file living in tmpfs 2158 * 2159 * @name: name for dentry (to be seen in /proc/<pid>/maps 2160 * @size: size to be set for the file 2161 * 2162 */ 2163struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2164{ 2165 int error; 2166 struct file *file; 2167 struct inode *inode; 2168 struct dentry *dentry, *root; 2169 struct qstr this; 2170 2171 if (IS_ERR(shm_mnt)) 2172 return (void *)shm_mnt; 2173 2174 if (size < 0 || size > SHMEM_MAX_BYTES) 2175 return ERR_PTR(-EINVAL); 2176 2177 if (shmem_acct_size(flags, size)) 2178 return ERR_PTR(-ENOMEM); 2179 2180 error = -ENOMEM; 2181 this.name = name; 2182 this.len = strlen(name); 2183 this.hash = 0; /* will go */ 2184 root = shm_mnt->mnt_root; 2185 dentry = d_alloc(root, &this); 2186 if (!dentry) 2187 goto put_memory; 2188 2189 error = -ENFILE; 2190 file = get_empty_filp(); 2191 if (!file) 2192 goto put_dentry; 2193 2194 error = -ENOSPC; 2195 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2196 if (!inode) 2197 goto close_file; 2198 2199 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2200 d_instantiate(dentry, inode); 2201 inode->i_size = size; 2202 inode->i_nlink = 0; /* It is unlinked */ 2203 file->f_vfsmnt = mntget(shm_mnt); 2204 file->f_dentry = dentry; 2205 file->f_mapping = inode->i_mapping; 2206 file->f_op = &shmem_file_operations; 2207 file->f_mode = FMODE_WRITE | FMODE_READ; 2208 return file; 2209 2210close_file: 2211 put_filp(file); 2212put_dentry: 2213 dput(dentry); 2214put_memory: 2215 shmem_unacct_size(flags, size); 2216 return ERR_PTR(error); 2217} 2218 2219/* 2220 * shmem_zero_setup - setup a shared anonymous mapping 2221 * 2222 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2223 */ 2224int shmem_zero_setup(struct vm_area_struct *vma) 2225{ 2226 struct file *file; 2227 loff_t size = vma->vm_end - vma->vm_start; 2228 2229 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2230 if (IS_ERR(file)) 2231 return PTR_ERR(file); 2232 2233 if (vma->vm_file) 2234 fput(vma->vm_file); 2235 vma->vm_file = file; 2236 vma->vm_ops = &shmem_vm_ops; 2237 return 0; 2238} 2239