shmem.c revision ba52de123d454b57369f291348266d86f4b35070
1/* 2 * Resizable virtual memory filesystem for Linux. 3 * 4 * Copyright (C) 2000 Linus Torvalds. 5 * 2000 Transmeta Corp. 6 * 2000-2001 Christoph Rohland 7 * 2000-2001 SAP AG 8 * 2002 Red Hat Inc. 9 * Copyright (C) 2002-2005 Hugh Dickins. 10 * Copyright (C) 2002-2005 VERITAS Software Corporation. 11 * Copyright (C) 2004 Andi Kleen, SuSE Labs 12 * 13 * Extended attribute support for tmpfs: 14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> 15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> 16 * 17 * This file is released under the GPL. 18 */ 19 20/* 21 * This virtual memory filesystem is heavily based on the ramfs. It 22 * extends ramfs by the ability to use swap and honor resource limits 23 * which makes it a completely usable filesystem. 24 */ 25 26#include <linux/module.h> 27#include <linux/init.h> 28#include <linux/fs.h> 29#include <linux/mm.h> 30#include <linux/mman.h> 31#include <linux/file.h> 32#include <linux/swap.h> 33#include <linux/pagemap.h> 34#include <linux/string.h> 35#include <linux/slab.h> 36#include <linux/backing-dev.h> 37#include <linux/shmem_fs.h> 38#include <linux/mount.h> 39#include <linux/writeback.h> 40#include <linux/vfs.h> 41#include <linux/blkdev.h> 42#include <linux/security.h> 43#include <linux/swapops.h> 44#include <linux/mempolicy.h> 45#include <linux/namei.h> 46#include <linux/ctype.h> 47#include <linux/migrate.h> 48#include <linux/highmem.h> 49 50#include <asm/uaccess.h> 51#include <asm/div64.h> 52#include <asm/pgtable.h> 53 54/* This magic number is used in glibc for posix shared memory */ 55#define TMPFS_MAGIC 0x01021994 56 57#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) 58#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) 59#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) 60 61#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) 62#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT) 63 64#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) 65 66/* info->flags needs VM_flags to handle pagein/truncate races efficiently */ 67#define SHMEM_PAGEIN VM_READ 68#define SHMEM_TRUNCATE VM_WRITE 69 70/* Definition to limit shmem_truncate's steps between cond_rescheds */ 71#define LATENCY_LIMIT 64 72 73/* Pretend that each entry is of this size in directory's i_size */ 74#define BOGO_DIRENT_SIZE 20 75 76/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ 77enum sgp_type { 78 SGP_QUICK, /* don't try more than file page cache lookup */ 79 SGP_READ, /* don't exceed i_size, don't allocate page */ 80 SGP_CACHE, /* don't exceed i_size, may allocate page */ 81 SGP_WRITE, /* may exceed i_size, may allocate page */ 82}; 83 84static int shmem_getpage(struct inode *inode, unsigned long idx, 85 struct page **pagep, enum sgp_type sgp, int *type); 86 87static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) 88{ 89 /* 90 * The above definition of ENTRIES_PER_PAGE, and the use of 91 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 92 * might be reconsidered if it ever diverges from PAGE_SIZE. 93 */ 94 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT); 95} 96 97static inline void shmem_dir_free(struct page *page) 98{ 99 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 100} 101 102static struct page **shmem_dir_map(struct page *page) 103{ 104 return (struct page **)kmap_atomic(page, KM_USER0); 105} 106 107static inline void shmem_dir_unmap(struct page **dir) 108{ 109 kunmap_atomic(dir, KM_USER0); 110} 111 112static swp_entry_t *shmem_swp_map(struct page *page) 113{ 114 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 115} 116 117static inline void shmem_swp_balance_unmap(void) 118{ 119 /* 120 * When passing a pointer to an i_direct entry, to code which 121 * also handles indirect entries and so will shmem_swp_unmap, 122 * we must arrange for the preempt count to remain in balance. 123 * What kmap_atomic of a lowmem page does depends on config 124 * and architecture, so pretend to kmap_atomic some lowmem page. 125 */ 126 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 127} 128 129static inline void shmem_swp_unmap(swp_entry_t *entry) 130{ 131 kunmap_atomic(entry, KM_USER1); 132} 133 134static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 135{ 136 return sb->s_fs_info; 137} 138 139/* 140 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 141 * for shared memory and for shared anonymous (/dev/zero) mappings 142 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 143 * consistent with the pre-accounting of private mappings ... 144 */ 145static inline int shmem_acct_size(unsigned long flags, loff_t size) 146{ 147 return (flags & VM_ACCOUNT)? 148 security_vm_enough_memory(VM_ACCT(size)): 0; 149} 150 151static inline void shmem_unacct_size(unsigned long flags, loff_t size) 152{ 153 if (flags & VM_ACCOUNT) 154 vm_unacct_memory(VM_ACCT(size)); 155} 156 157/* 158 * ... whereas tmpfs objects are accounted incrementally as 159 * pages are allocated, in order to allow huge sparse files. 160 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 161 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 162 */ 163static inline int shmem_acct_block(unsigned long flags) 164{ 165 return (flags & VM_ACCOUNT)? 166 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE)); 167} 168 169static inline void shmem_unacct_blocks(unsigned long flags, long pages) 170{ 171 if (!(flags & VM_ACCOUNT)) 172 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 173} 174 175static struct super_operations shmem_ops; 176static const struct address_space_operations shmem_aops; 177static struct file_operations shmem_file_operations; 178static struct inode_operations shmem_inode_operations; 179static struct inode_operations shmem_dir_inode_operations; 180static struct vm_operations_struct shmem_vm_ops; 181 182static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 183 .ra_pages = 0, /* No readahead */ 184 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, 185 .unplug_io_fn = default_unplug_io_fn, 186}; 187 188static LIST_HEAD(shmem_swaplist); 189static DEFINE_SPINLOCK(shmem_swaplist_lock); 190 191static void shmem_free_blocks(struct inode *inode, long pages) 192{ 193 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 194 if (sbinfo->max_blocks) { 195 spin_lock(&sbinfo->stat_lock); 196 sbinfo->free_blocks += pages; 197 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 198 spin_unlock(&sbinfo->stat_lock); 199 } 200} 201 202/* 203 * shmem_recalc_inode - recalculate the size of an inode 204 * 205 * @inode: inode to recalc 206 * 207 * We have to calculate the free blocks since the mm can drop 208 * undirtied hole pages behind our back. 209 * 210 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 211 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 212 * 213 * It has to be called with the spinlock held. 214 */ 215static void shmem_recalc_inode(struct inode *inode) 216{ 217 struct shmem_inode_info *info = SHMEM_I(inode); 218 long freed; 219 220 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 221 if (freed > 0) { 222 info->alloced -= freed; 223 shmem_unacct_blocks(info->flags, freed); 224 shmem_free_blocks(inode, freed); 225 } 226} 227 228/* 229 * shmem_swp_entry - find the swap vector position in the info structure 230 * 231 * @info: info structure for the inode 232 * @index: index of the page to find 233 * @page: optional page to add to the structure. Has to be preset to 234 * all zeros 235 * 236 * If there is no space allocated yet it will return NULL when 237 * page is NULL, else it will use the page for the needed block, 238 * setting it to NULL on return to indicate that it has been used. 239 * 240 * The swap vector is organized the following way: 241 * 242 * There are SHMEM_NR_DIRECT entries directly stored in the 243 * shmem_inode_info structure. So small files do not need an addional 244 * allocation. 245 * 246 * For pages with index > SHMEM_NR_DIRECT there is the pointer 247 * i_indirect which points to a page which holds in the first half 248 * doubly indirect blocks, in the second half triple indirect blocks: 249 * 250 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 251 * following layout (for SHMEM_NR_DIRECT == 16): 252 * 253 * i_indirect -> dir --> 16-19 254 * | +-> 20-23 255 * | 256 * +-->dir2 --> 24-27 257 * | +-> 28-31 258 * | +-> 32-35 259 * | +-> 36-39 260 * | 261 * +-->dir3 --> 40-43 262 * +-> 44-47 263 * +-> 48-51 264 * +-> 52-55 265 */ 266static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 267{ 268 unsigned long offset; 269 struct page **dir; 270 struct page *subdir; 271 272 if (index < SHMEM_NR_DIRECT) { 273 shmem_swp_balance_unmap(); 274 return info->i_direct+index; 275 } 276 if (!info->i_indirect) { 277 if (page) { 278 info->i_indirect = *page; 279 *page = NULL; 280 } 281 return NULL; /* need another page */ 282 } 283 284 index -= SHMEM_NR_DIRECT; 285 offset = index % ENTRIES_PER_PAGE; 286 index /= ENTRIES_PER_PAGE; 287 dir = shmem_dir_map(info->i_indirect); 288 289 if (index >= ENTRIES_PER_PAGE/2) { 290 index -= ENTRIES_PER_PAGE/2; 291 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 292 index %= ENTRIES_PER_PAGE; 293 subdir = *dir; 294 if (!subdir) { 295 if (page) { 296 *dir = *page; 297 *page = NULL; 298 } 299 shmem_dir_unmap(dir); 300 return NULL; /* need another page */ 301 } 302 shmem_dir_unmap(dir); 303 dir = shmem_dir_map(subdir); 304 } 305 306 dir += index; 307 subdir = *dir; 308 if (!subdir) { 309 if (!page || !(subdir = *page)) { 310 shmem_dir_unmap(dir); 311 return NULL; /* need a page */ 312 } 313 *dir = subdir; 314 *page = NULL; 315 } 316 shmem_dir_unmap(dir); 317 return shmem_swp_map(subdir) + offset; 318} 319 320static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 321{ 322 long incdec = value? 1: -1; 323 324 entry->val = value; 325 info->swapped += incdec; 326 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { 327 struct page *page = kmap_atomic_to_page(entry); 328 set_page_private(page, page_private(page) + incdec); 329 } 330} 331 332/* 333 * shmem_swp_alloc - get the position of the swap entry for the page. 334 * If it does not exist allocate the entry. 335 * 336 * @info: info structure for the inode 337 * @index: index of the page to find 338 * @sgp: check and recheck i_size? skip allocation? 339 */ 340static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 341{ 342 struct inode *inode = &info->vfs_inode; 343 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 344 struct page *page = NULL; 345 swp_entry_t *entry; 346 347 if (sgp != SGP_WRITE && 348 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 349 return ERR_PTR(-EINVAL); 350 351 while (!(entry = shmem_swp_entry(info, index, &page))) { 352 if (sgp == SGP_READ) 353 return shmem_swp_map(ZERO_PAGE(0)); 354 /* 355 * Test free_blocks against 1 not 0, since we have 1 data 356 * page (and perhaps indirect index pages) yet to allocate: 357 * a waste to allocate index if we cannot allocate data. 358 */ 359 if (sbinfo->max_blocks) { 360 spin_lock(&sbinfo->stat_lock); 361 if (sbinfo->free_blocks <= 1) { 362 spin_unlock(&sbinfo->stat_lock); 363 return ERR_PTR(-ENOSPC); 364 } 365 sbinfo->free_blocks--; 366 inode->i_blocks += BLOCKS_PER_PAGE; 367 spin_unlock(&sbinfo->stat_lock); 368 } 369 370 spin_unlock(&info->lock); 371 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO); 372 if (page) 373 set_page_private(page, 0); 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_range(struct inode *inode, loff_t start, loff_t end) 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 int punch_hole = 0; 481 482 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 483 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 484 if (idx >= info->next_index) 485 return; 486 487 spin_lock(&info->lock); 488 info->flags |= SHMEM_TRUNCATE; 489 if (likely(end == (loff_t) -1)) { 490 limit = info->next_index; 491 info->next_index = idx; 492 } else { 493 limit = (end + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 494 if (limit > info->next_index) 495 limit = info->next_index; 496 punch_hole = 1; 497 } 498 499 topdir = info->i_indirect; 500 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { 501 info->i_indirect = NULL; 502 nr_pages_to_free++; 503 list_add(&topdir->lru, &pages_to_free); 504 } 505 spin_unlock(&info->lock); 506 507 if (info->swapped && idx < SHMEM_NR_DIRECT) { 508 ptr = info->i_direct; 509 size = limit; 510 if (size > SHMEM_NR_DIRECT) 511 size = SHMEM_NR_DIRECT; 512 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size); 513 } 514 if (!topdir) 515 goto done2; 516 517 BUG_ON(limit <= SHMEM_NR_DIRECT); 518 limit -= SHMEM_NR_DIRECT; 519 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 520 offset = idx % ENTRIES_PER_PAGE; 521 idx -= offset; 522 523 dir = shmem_dir_map(topdir); 524 stage = ENTRIES_PER_PAGEPAGE/2; 525 if (idx < ENTRIES_PER_PAGEPAGE/2) { 526 middir = topdir; 527 diroff = idx/ENTRIES_PER_PAGE; 528 } else { 529 dir += ENTRIES_PER_PAGE/2; 530 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 531 while (stage <= idx) 532 stage += ENTRIES_PER_PAGEPAGE; 533 middir = *dir; 534 if (*dir) { 535 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 536 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 537 if (!diroff && !offset) { 538 *dir = NULL; 539 nr_pages_to_free++; 540 list_add(&middir->lru, &pages_to_free); 541 } 542 shmem_dir_unmap(dir); 543 dir = shmem_dir_map(middir); 544 } else { 545 diroff = 0; 546 offset = 0; 547 idx = stage; 548 } 549 } 550 551 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 552 if (unlikely(idx == stage)) { 553 shmem_dir_unmap(dir); 554 dir = shmem_dir_map(topdir) + 555 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 556 while (!*dir) { 557 dir++; 558 idx += ENTRIES_PER_PAGEPAGE; 559 if (idx >= limit) 560 goto done1; 561 } 562 stage = idx + ENTRIES_PER_PAGEPAGE; 563 middir = *dir; 564 *dir = NULL; 565 nr_pages_to_free++; 566 list_add(&middir->lru, &pages_to_free); 567 shmem_dir_unmap(dir); 568 cond_resched(); 569 dir = shmem_dir_map(middir); 570 diroff = 0; 571 } 572 subdir = dir[diroff]; 573 if (subdir && page_private(subdir)) { 574 size = limit - idx; 575 if (size > ENTRIES_PER_PAGE) 576 size = ENTRIES_PER_PAGE; 577 freed = shmem_map_and_free_swp(subdir, 578 offset, size, &dir); 579 if (!dir) 580 dir = shmem_dir_map(middir); 581 nr_swaps_freed += freed; 582 if (offset) 583 spin_lock(&info->lock); 584 set_page_private(subdir, page_private(subdir) - freed); 585 if (offset) 586 spin_unlock(&info->lock); 587 if (!punch_hole) 588 BUG_ON(page_private(subdir) > offset); 589 } 590 if (offset) 591 offset = 0; 592 else if (subdir && !page_private(subdir)) { 593 dir[diroff] = NULL; 594 nr_pages_to_free++; 595 list_add(&subdir->lru, &pages_to_free); 596 } 597 } 598done1: 599 shmem_dir_unmap(dir); 600done2: 601 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 602 /* 603 * Call truncate_inode_pages again: racing shmem_unuse_inode 604 * may have swizzled a page in from swap since vmtruncate or 605 * generic_delete_inode did it, before we lowered next_index. 606 * Also, though shmem_getpage checks i_size before adding to 607 * cache, no recheck after: so fix the narrow window there too. 608 */ 609 truncate_inode_pages_range(inode->i_mapping, start, end); 610 } 611 612 spin_lock(&info->lock); 613 info->flags &= ~SHMEM_TRUNCATE; 614 info->swapped -= nr_swaps_freed; 615 if (nr_pages_to_free) 616 shmem_free_blocks(inode, nr_pages_to_free); 617 shmem_recalc_inode(inode); 618 spin_unlock(&info->lock); 619 620 /* 621 * Empty swap vector directory pages to be freed? 622 */ 623 if (!list_empty(&pages_to_free)) { 624 pages_to_free.prev->next = NULL; 625 shmem_free_pages(pages_to_free.next); 626 } 627} 628 629static void shmem_truncate(struct inode *inode) 630{ 631 shmem_truncate_range(inode, inode->i_size, (loff_t)-1); 632} 633 634static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 635{ 636 struct inode *inode = dentry->d_inode; 637 struct page *page = NULL; 638 int error; 639 640 if (attr->ia_valid & ATTR_SIZE) { 641 if (attr->ia_size < inode->i_size) { 642 /* 643 * If truncating down to a partial page, then 644 * if that page is already allocated, hold it 645 * in memory until the truncation is over, so 646 * truncate_partial_page cannnot miss it were 647 * it assigned to swap. 648 */ 649 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { 650 (void) shmem_getpage(inode, 651 attr->ia_size>>PAGE_CACHE_SHIFT, 652 &page, SGP_READ, NULL); 653 } 654 /* 655 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 656 * detect if any pages might have been added to cache 657 * after truncate_inode_pages. But we needn't bother 658 * if it's being fully truncated to zero-length: the 659 * nrpages check is efficient enough in that case. 660 */ 661 if (attr->ia_size) { 662 struct shmem_inode_info *info = SHMEM_I(inode); 663 spin_lock(&info->lock); 664 info->flags &= ~SHMEM_PAGEIN; 665 spin_unlock(&info->lock); 666 } 667 } 668 } 669 670 error = inode_change_ok(inode, attr); 671 if (!error) 672 error = inode_setattr(inode, attr); 673 if (page) 674 page_cache_release(page); 675 return error; 676} 677 678static void shmem_delete_inode(struct inode *inode) 679{ 680 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 681 struct shmem_inode_info *info = SHMEM_I(inode); 682 683 if (inode->i_op->truncate == shmem_truncate) { 684 truncate_inode_pages(inode->i_mapping, 0); 685 shmem_unacct_size(info->flags, inode->i_size); 686 inode->i_size = 0; 687 shmem_truncate(inode); 688 if (!list_empty(&info->swaplist)) { 689 spin_lock(&shmem_swaplist_lock); 690 list_del_init(&info->swaplist); 691 spin_unlock(&shmem_swaplist_lock); 692 } 693 } 694 BUG_ON(inode->i_blocks); 695 if (sbinfo->max_inodes) { 696 spin_lock(&sbinfo->stat_lock); 697 sbinfo->free_inodes++; 698 spin_unlock(&sbinfo->stat_lock); 699 } 700 clear_inode(inode); 701} 702 703static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 704{ 705 swp_entry_t *ptr; 706 707 for (ptr = dir; ptr < edir; ptr++) { 708 if (ptr->val == entry.val) 709 return ptr - dir; 710 } 711 return -1; 712} 713 714static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 715{ 716 struct inode *inode; 717 unsigned long idx; 718 unsigned long size; 719 unsigned long limit; 720 unsigned long stage; 721 struct page **dir; 722 struct page *subdir; 723 swp_entry_t *ptr; 724 int offset; 725 726 idx = 0; 727 ptr = info->i_direct; 728 spin_lock(&info->lock); 729 limit = info->next_index; 730 size = limit; 731 if (size > SHMEM_NR_DIRECT) 732 size = SHMEM_NR_DIRECT; 733 offset = shmem_find_swp(entry, ptr, ptr+size); 734 if (offset >= 0) { 735 shmem_swp_balance_unmap(); 736 goto found; 737 } 738 if (!info->i_indirect) 739 goto lost2; 740 741 dir = shmem_dir_map(info->i_indirect); 742 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 743 744 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 745 if (unlikely(idx == stage)) { 746 shmem_dir_unmap(dir-1); 747 dir = shmem_dir_map(info->i_indirect) + 748 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 749 while (!*dir) { 750 dir++; 751 idx += ENTRIES_PER_PAGEPAGE; 752 if (idx >= limit) 753 goto lost1; 754 } 755 stage = idx + ENTRIES_PER_PAGEPAGE; 756 subdir = *dir; 757 shmem_dir_unmap(dir); 758 dir = shmem_dir_map(subdir); 759 } 760 subdir = *dir; 761 if (subdir && page_private(subdir)) { 762 ptr = shmem_swp_map(subdir); 763 size = limit - idx; 764 if (size > ENTRIES_PER_PAGE) 765 size = ENTRIES_PER_PAGE; 766 offset = shmem_find_swp(entry, ptr, ptr+size); 767 if (offset >= 0) { 768 shmem_dir_unmap(dir); 769 goto found; 770 } 771 shmem_swp_unmap(ptr); 772 } 773 } 774lost1: 775 shmem_dir_unmap(dir-1); 776lost2: 777 spin_unlock(&info->lock); 778 return 0; 779found: 780 idx += offset; 781 inode = &info->vfs_inode; 782 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) { 783 info->flags |= SHMEM_PAGEIN; 784 shmem_swp_set(info, ptr + offset, 0); 785 } 786 shmem_swp_unmap(ptr); 787 spin_unlock(&info->lock); 788 /* 789 * Decrement swap count even when the entry is left behind: 790 * try_to_unuse will skip over mms, then reincrement count. 791 */ 792 swap_free(entry); 793 return 1; 794} 795 796/* 797 * shmem_unuse() search for an eventually swapped out shmem page. 798 */ 799int shmem_unuse(swp_entry_t entry, struct page *page) 800{ 801 struct list_head *p, *next; 802 struct shmem_inode_info *info; 803 int found = 0; 804 805 spin_lock(&shmem_swaplist_lock); 806 list_for_each_safe(p, next, &shmem_swaplist) { 807 info = list_entry(p, struct shmem_inode_info, swaplist); 808 if (!info->swapped) 809 list_del_init(&info->swaplist); 810 else if (shmem_unuse_inode(info, entry, page)) { 811 /* move head to start search for next from here */ 812 list_move_tail(&shmem_swaplist, &info->swaplist); 813 found = 1; 814 break; 815 } 816 } 817 spin_unlock(&shmem_swaplist_lock); 818 return found; 819} 820 821/* 822 * Move the page from the page cache to the swap cache. 823 */ 824static int shmem_writepage(struct page *page, struct writeback_control *wbc) 825{ 826 struct shmem_inode_info *info; 827 swp_entry_t *entry, swap; 828 struct address_space *mapping; 829 unsigned long index; 830 struct inode *inode; 831 832 BUG_ON(!PageLocked(page)); 833 BUG_ON(page_mapped(page)); 834 835 mapping = page->mapping; 836 index = page->index; 837 inode = mapping->host; 838 info = SHMEM_I(inode); 839 if (info->flags & VM_LOCKED) 840 goto redirty; 841 swap = get_swap_page(); 842 if (!swap.val) 843 goto redirty; 844 845 spin_lock(&info->lock); 846 shmem_recalc_inode(inode); 847 if (index >= info->next_index) { 848 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 849 goto unlock; 850 } 851 entry = shmem_swp_entry(info, index, NULL); 852 BUG_ON(!entry); 853 BUG_ON(entry->val); 854 855 if (move_to_swap_cache(page, swap) == 0) { 856 shmem_swp_set(info, entry, swap.val); 857 shmem_swp_unmap(entry); 858 spin_unlock(&info->lock); 859 if (list_empty(&info->swaplist)) { 860 spin_lock(&shmem_swaplist_lock); 861 /* move instead of add in case we're racing */ 862 list_move_tail(&info->swaplist, &shmem_swaplist); 863 spin_unlock(&shmem_swaplist_lock); 864 } 865 unlock_page(page); 866 return 0; 867 } 868 869 shmem_swp_unmap(entry); 870unlock: 871 spin_unlock(&info->lock); 872 swap_free(swap); 873redirty: 874 set_page_dirty(page); 875 return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */ 876} 877 878#ifdef CONFIG_NUMA 879static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 880{ 881 char *nodelist = strchr(value, ':'); 882 int err = 1; 883 884 if (nodelist) { 885 /* NUL-terminate policy string */ 886 *nodelist++ = '\0'; 887 if (nodelist_parse(nodelist, *policy_nodes)) 888 goto out; 889 } 890 if (!strcmp(value, "default")) { 891 *policy = MPOL_DEFAULT; 892 /* Don't allow a nodelist */ 893 if (!nodelist) 894 err = 0; 895 } else if (!strcmp(value, "prefer")) { 896 *policy = MPOL_PREFERRED; 897 /* Insist on a nodelist of one node only */ 898 if (nodelist) { 899 char *rest = nodelist; 900 while (isdigit(*rest)) 901 rest++; 902 if (!*rest) 903 err = 0; 904 } 905 } else if (!strcmp(value, "bind")) { 906 *policy = MPOL_BIND; 907 /* Insist on a nodelist */ 908 if (nodelist) 909 err = 0; 910 } else if (!strcmp(value, "interleave")) { 911 *policy = MPOL_INTERLEAVE; 912 /* Default to nodes online if no nodelist */ 913 if (!nodelist) 914 *policy_nodes = node_online_map; 915 err = 0; 916 } 917out: 918 /* Restore string for error message */ 919 if (nodelist) 920 *--nodelist = ':'; 921 return err; 922} 923 924static struct page *shmem_swapin_async(struct shared_policy *p, 925 swp_entry_t entry, unsigned long idx) 926{ 927 struct page *page; 928 struct vm_area_struct pvma; 929 930 /* Create a pseudo vma that just contains the policy */ 931 memset(&pvma, 0, sizeof(struct vm_area_struct)); 932 pvma.vm_end = PAGE_SIZE; 933 pvma.vm_pgoff = idx; 934 pvma.vm_policy = mpol_shared_policy_lookup(p, idx); 935 page = read_swap_cache_async(entry, &pvma, 0); 936 mpol_free(pvma.vm_policy); 937 return page; 938} 939 940struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry, 941 unsigned long idx) 942{ 943 struct shared_policy *p = &info->policy; 944 int i, num; 945 struct page *page; 946 unsigned long offset; 947 948 num = valid_swaphandles(entry, &offset); 949 for (i = 0; i < num; offset++, i++) { 950 page = shmem_swapin_async(p, 951 swp_entry(swp_type(entry), offset), idx); 952 if (!page) 953 break; 954 page_cache_release(page); 955 } 956 lru_add_drain(); /* Push any new pages onto the LRU now */ 957 return shmem_swapin_async(p, entry, idx); 958} 959 960static struct page * 961shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, 962 unsigned long idx) 963{ 964 struct vm_area_struct pvma; 965 struct page *page; 966 967 memset(&pvma, 0, sizeof(struct vm_area_struct)); 968 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 969 pvma.vm_pgoff = idx; 970 pvma.vm_end = PAGE_SIZE; 971 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0); 972 mpol_free(pvma.vm_policy); 973 return page; 974} 975#else 976static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 977{ 978 return 1; 979} 980 981static inline struct page * 982shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx) 983{ 984 swapin_readahead(entry, 0, NULL); 985 return read_swap_cache_async(entry, NULL, 0); 986} 987 988static inline struct page * 989shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx) 990{ 991 return alloc_page(gfp | __GFP_ZERO); 992} 993#endif 994 995/* 996 * shmem_getpage - either get the page from swap or allocate a new one 997 * 998 * If we allocate a new one we do not mark it dirty. That's up to the 999 * vm. If we swap it in we mark it dirty since we also free the swap 1000 * entry since a page cannot live in both the swap and page cache 1001 */ 1002static int shmem_getpage(struct inode *inode, unsigned long idx, 1003 struct page **pagep, enum sgp_type sgp, int *type) 1004{ 1005 struct address_space *mapping = inode->i_mapping; 1006 struct shmem_inode_info *info = SHMEM_I(inode); 1007 struct shmem_sb_info *sbinfo; 1008 struct page *filepage = *pagep; 1009 struct page *swappage; 1010 swp_entry_t *entry; 1011 swp_entry_t swap; 1012 int error; 1013 1014 if (idx >= SHMEM_MAX_INDEX) 1015 return -EFBIG; 1016 /* 1017 * Normally, filepage is NULL on entry, and either found 1018 * uptodate immediately, or allocated and zeroed, or read 1019 * in under swappage, which is then assigned to filepage. 1020 * But shmem_prepare_write passes in a locked filepage, 1021 * which may be found not uptodate by other callers too, 1022 * and may need to be copied from the swappage read in. 1023 */ 1024repeat: 1025 if (!filepage) 1026 filepage = find_lock_page(mapping, idx); 1027 if (filepage && PageUptodate(filepage)) 1028 goto done; 1029 error = 0; 1030 if (sgp == SGP_QUICK) 1031 goto failed; 1032 1033 spin_lock(&info->lock); 1034 shmem_recalc_inode(inode); 1035 entry = shmem_swp_alloc(info, idx, sgp); 1036 if (IS_ERR(entry)) { 1037 spin_unlock(&info->lock); 1038 error = PTR_ERR(entry); 1039 goto failed; 1040 } 1041 swap = *entry; 1042 1043 if (swap.val) { 1044 /* Look it up and read it in.. */ 1045 swappage = lookup_swap_cache(swap); 1046 if (!swappage) { 1047 shmem_swp_unmap(entry); 1048 /* here we actually do the io */ 1049 if (type && *type == VM_FAULT_MINOR) { 1050 __count_vm_event(PGMAJFAULT); 1051 *type = VM_FAULT_MAJOR; 1052 } 1053 spin_unlock(&info->lock); 1054 swappage = shmem_swapin(info, swap, idx); 1055 if (!swappage) { 1056 spin_lock(&info->lock); 1057 entry = shmem_swp_alloc(info, idx, sgp); 1058 if (IS_ERR(entry)) 1059 error = PTR_ERR(entry); 1060 else { 1061 if (entry->val == swap.val) 1062 error = -ENOMEM; 1063 shmem_swp_unmap(entry); 1064 } 1065 spin_unlock(&info->lock); 1066 if (error) 1067 goto failed; 1068 goto repeat; 1069 } 1070 wait_on_page_locked(swappage); 1071 page_cache_release(swappage); 1072 goto repeat; 1073 } 1074 1075 /* We have to do this with page locked to prevent races */ 1076 if (TestSetPageLocked(swappage)) { 1077 shmem_swp_unmap(entry); 1078 spin_unlock(&info->lock); 1079 wait_on_page_locked(swappage); 1080 page_cache_release(swappage); 1081 goto repeat; 1082 } 1083 if (PageWriteback(swappage)) { 1084 shmem_swp_unmap(entry); 1085 spin_unlock(&info->lock); 1086 wait_on_page_writeback(swappage); 1087 unlock_page(swappage); 1088 page_cache_release(swappage); 1089 goto repeat; 1090 } 1091 if (!PageUptodate(swappage)) { 1092 shmem_swp_unmap(entry); 1093 spin_unlock(&info->lock); 1094 unlock_page(swappage); 1095 page_cache_release(swappage); 1096 error = -EIO; 1097 goto failed; 1098 } 1099 1100 if (filepage) { 1101 shmem_swp_set(info, entry, 0); 1102 shmem_swp_unmap(entry); 1103 delete_from_swap_cache(swappage); 1104 spin_unlock(&info->lock); 1105 copy_highpage(filepage, swappage); 1106 unlock_page(swappage); 1107 page_cache_release(swappage); 1108 flush_dcache_page(filepage); 1109 SetPageUptodate(filepage); 1110 set_page_dirty(filepage); 1111 swap_free(swap); 1112 } else if (!(error = move_from_swap_cache( 1113 swappage, idx, mapping))) { 1114 info->flags |= SHMEM_PAGEIN; 1115 shmem_swp_set(info, entry, 0); 1116 shmem_swp_unmap(entry); 1117 spin_unlock(&info->lock); 1118 filepage = swappage; 1119 swap_free(swap); 1120 } else { 1121 shmem_swp_unmap(entry); 1122 spin_unlock(&info->lock); 1123 unlock_page(swappage); 1124 page_cache_release(swappage); 1125 if (error == -ENOMEM) { 1126 /* let kswapd refresh zone for GFP_ATOMICs */ 1127 blk_congestion_wait(WRITE, HZ/50); 1128 } 1129 goto repeat; 1130 } 1131 } else if (sgp == SGP_READ && !filepage) { 1132 shmem_swp_unmap(entry); 1133 filepage = find_get_page(mapping, idx); 1134 if (filepage && 1135 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1136 spin_unlock(&info->lock); 1137 wait_on_page_locked(filepage); 1138 page_cache_release(filepage); 1139 filepage = NULL; 1140 goto repeat; 1141 } 1142 spin_unlock(&info->lock); 1143 } else { 1144 shmem_swp_unmap(entry); 1145 sbinfo = SHMEM_SB(inode->i_sb); 1146 if (sbinfo->max_blocks) { 1147 spin_lock(&sbinfo->stat_lock); 1148 if (sbinfo->free_blocks == 0 || 1149 shmem_acct_block(info->flags)) { 1150 spin_unlock(&sbinfo->stat_lock); 1151 spin_unlock(&info->lock); 1152 error = -ENOSPC; 1153 goto failed; 1154 } 1155 sbinfo->free_blocks--; 1156 inode->i_blocks += BLOCKS_PER_PAGE; 1157 spin_unlock(&sbinfo->stat_lock); 1158 } else if (shmem_acct_block(info->flags)) { 1159 spin_unlock(&info->lock); 1160 error = -ENOSPC; 1161 goto failed; 1162 } 1163 1164 if (!filepage) { 1165 spin_unlock(&info->lock); 1166 filepage = shmem_alloc_page(mapping_gfp_mask(mapping), 1167 info, 1168 idx); 1169 if (!filepage) { 1170 shmem_unacct_blocks(info->flags, 1); 1171 shmem_free_blocks(inode, 1); 1172 error = -ENOMEM; 1173 goto failed; 1174 } 1175 1176 spin_lock(&info->lock); 1177 entry = shmem_swp_alloc(info, idx, sgp); 1178 if (IS_ERR(entry)) 1179 error = PTR_ERR(entry); 1180 else { 1181 swap = *entry; 1182 shmem_swp_unmap(entry); 1183 } 1184 if (error || swap.val || 0 != add_to_page_cache_lru( 1185 filepage, mapping, idx, GFP_ATOMIC)) { 1186 spin_unlock(&info->lock); 1187 page_cache_release(filepage); 1188 shmem_unacct_blocks(info->flags, 1); 1189 shmem_free_blocks(inode, 1); 1190 filepage = NULL; 1191 if (error) 1192 goto failed; 1193 goto repeat; 1194 } 1195 info->flags |= SHMEM_PAGEIN; 1196 } 1197 1198 info->alloced++; 1199 spin_unlock(&info->lock); 1200 flush_dcache_page(filepage); 1201 SetPageUptodate(filepage); 1202 } 1203done: 1204 if (*pagep != filepage) { 1205 unlock_page(filepage); 1206 *pagep = filepage; 1207 } 1208 return 0; 1209 1210failed: 1211 if (*pagep != filepage) { 1212 unlock_page(filepage); 1213 page_cache_release(filepage); 1214 } 1215 return error; 1216} 1217 1218struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type) 1219{ 1220 struct inode *inode = vma->vm_file->f_dentry->d_inode; 1221 struct page *page = NULL; 1222 unsigned long idx; 1223 int error; 1224 1225 idx = (address - vma->vm_start) >> PAGE_SHIFT; 1226 idx += vma->vm_pgoff; 1227 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT; 1228 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1229 return NOPAGE_SIGBUS; 1230 1231 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type); 1232 if (error) 1233 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS; 1234 1235 mark_page_accessed(page); 1236 return page; 1237} 1238 1239static int shmem_populate(struct vm_area_struct *vma, 1240 unsigned long addr, unsigned long len, 1241 pgprot_t prot, unsigned long pgoff, int nonblock) 1242{ 1243 struct inode *inode = vma->vm_file->f_dentry->d_inode; 1244 struct mm_struct *mm = vma->vm_mm; 1245 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE; 1246 unsigned long size; 1247 1248 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; 1249 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size) 1250 return -EINVAL; 1251 1252 while ((long) len > 0) { 1253 struct page *page = NULL; 1254 int err; 1255 /* 1256 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE 1257 */ 1258 err = shmem_getpage(inode, pgoff, &page, sgp, NULL); 1259 if (err) 1260 return err; 1261 /* Page may still be null, but only if nonblock was set. */ 1262 if (page) { 1263 mark_page_accessed(page); 1264 err = install_page(mm, vma, addr, page, prot); 1265 if (err) { 1266 page_cache_release(page); 1267 return err; 1268 } 1269 } else if (vma->vm_flags & VM_NONLINEAR) { 1270 /* No page was found just because we can't read it in 1271 * now (being here implies nonblock != 0), but the page 1272 * may exist, so set the PTE to fault it in later. */ 1273 err = install_file_pte(mm, vma, addr, pgoff, prot); 1274 if (err) 1275 return err; 1276 } 1277 1278 len -= PAGE_SIZE; 1279 addr += PAGE_SIZE; 1280 pgoff++; 1281 } 1282 return 0; 1283} 1284 1285#ifdef CONFIG_NUMA 1286int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1287{ 1288 struct inode *i = vma->vm_file->f_dentry->d_inode; 1289 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1290} 1291 1292struct mempolicy * 1293shmem_get_policy(struct vm_area_struct *vma, unsigned long addr) 1294{ 1295 struct inode *i = vma->vm_file->f_dentry->d_inode; 1296 unsigned long idx; 1297 1298 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1299 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1300} 1301#endif 1302 1303int shmem_lock(struct file *file, int lock, struct user_struct *user) 1304{ 1305 struct inode *inode = file->f_dentry->d_inode; 1306 struct shmem_inode_info *info = SHMEM_I(inode); 1307 int retval = -ENOMEM; 1308 1309 spin_lock(&info->lock); 1310 if (lock && !(info->flags & VM_LOCKED)) { 1311 if (!user_shm_lock(inode->i_size, user)) 1312 goto out_nomem; 1313 info->flags |= VM_LOCKED; 1314 } 1315 if (!lock && (info->flags & VM_LOCKED) && user) { 1316 user_shm_unlock(inode->i_size, user); 1317 info->flags &= ~VM_LOCKED; 1318 } 1319 retval = 0; 1320out_nomem: 1321 spin_unlock(&info->lock); 1322 return retval; 1323} 1324 1325int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1326{ 1327 file_accessed(file); 1328 vma->vm_ops = &shmem_vm_ops; 1329 return 0; 1330} 1331 1332static struct inode * 1333shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1334{ 1335 struct inode *inode; 1336 struct shmem_inode_info *info; 1337 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1338 1339 if (sbinfo->max_inodes) { 1340 spin_lock(&sbinfo->stat_lock); 1341 if (!sbinfo->free_inodes) { 1342 spin_unlock(&sbinfo->stat_lock); 1343 return NULL; 1344 } 1345 sbinfo->free_inodes--; 1346 spin_unlock(&sbinfo->stat_lock); 1347 } 1348 1349 inode = new_inode(sb); 1350 if (inode) { 1351 inode->i_mode = mode; 1352 inode->i_uid = current->fsuid; 1353 inode->i_gid = current->fsgid; 1354 inode->i_blocks = 0; 1355 inode->i_mapping->a_ops = &shmem_aops; 1356 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1357 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1358 info = SHMEM_I(inode); 1359 memset(info, 0, (char *)inode - (char *)info); 1360 spin_lock_init(&info->lock); 1361 INIT_LIST_HEAD(&info->swaplist); 1362 1363 switch (mode & S_IFMT) { 1364 default: 1365 init_special_inode(inode, mode, dev); 1366 break; 1367 case S_IFREG: 1368 inode->i_op = &shmem_inode_operations; 1369 inode->i_fop = &shmem_file_operations; 1370 mpol_shared_policy_init(&info->policy, sbinfo->policy, 1371 &sbinfo->policy_nodes); 1372 break; 1373 case S_IFDIR: 1374 inode->i_nlink++; 1375 /* Some things misbehave if size == 0 on a directory */ 1376 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1377 inode->i_op = &shmem_dir_inode_operations; 1378 inode->i_fop = &simple_dir_operations; 1379 break; 1380 case S_IFLNK: 1381 /* 1382 * Must not load anything in the rbtree, 1383 * mpol_free_shared_policy will not be called. 1384 */ 1385 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, 1386 NULL); 1387 break; 1388 } 1389 } else if (sbinfo->max_inodes) { 1390 spin_lock(&sbinfo->stat_lock); 1391 sbinfo->free_inodes++; 1392 spin_unlock(&sbinfo->stat_lock); 1393 } 1394 return inode; 1395} 1396 1397#ifdef CONFIG_TMPFS 1398static struct inode_operations shmem_symlink_inode_operations; 1399static struct inode_operations shmem_symlink_inline_operations; 1400 1401/* 1402 * Normally tmpfs makes no use of shmem_prepare_write, but it 1403 * lets a tmpfs file be used read-write below the loop driver. 1404 */ 1405static int 1406shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to) 1407{ 1408 struct inode *inode = page->mapping->host; 1409 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL); 1410} 1411 1412static ssize_t 1413shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 1414{ 1415 struct inode *inode = file->f_dentry->d_inode; 1416 loff_t pos; 1417 unsigned long written; 1418 ssize_t err; 1419 1420 if ((ssize_t) count < 0) 1421 return -EINVAL; 1422 1423 if (!access_ok(VERIFY_READ, buf, count)) 1424 return -EFAULT; 1425 1426 mutex_lock(&inode->i_mutex); 1427 1428 pos = *ppos; 1429 written = 0; 1430 1431 err = generic_write_checks(file, &pos, &count, 0); 1432 if (err || !count) 1433 goto out; 1434 1435 err = remove_suid(file->f_dentry); 1436 if (err) 1437 goto out; 1438 1439 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 1440 1441 do { 1442 struct page *page = NULL; 1443 unsigned long bytes, index, offset; 1444 char *kaddr; 1445 int left; 1446 1447 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1448 index = pos >> PAGE_CACHE_SHIFT; 1449 bytes = PAGE_CACHE_SIZE - offset; 1450 if (bytes > count) 1451 bytes = count; 1452 1453 /* 1454 * We don't hold page lock across copy from user - 1455 * what would it guard against? - so no deadlock here. 1456 * But it still may be a good idea to prefault below. 1457 */ 1458 1459 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL); 1460 if (err) 1461 break; 1462 1463 left = bytes; 1464 if (PageHighMem(page)) { 1465 volatile unsigned char dummy; 1466 __get_user(dummy, buf); 1467 __get_user(dummy, buf + bytes - 1); 1468 1469 kaddr = kmap_atomic(page, KM_USER0); 1470 left = __copy_from_user_inatomic(kaddr + offset, 1471 buf, bytes); 1472 kunmap_atomic(kaddr, KM_USER0); 1473 } 1474 if (left) { 1475 kaddr = kmap(page); 1476 left = __copy_from_user(kaddr + offset, buf, bytes); 1477 kunmap(page); 1478 } 1479 1480 written += bytes; 1481 count -= bytes; 1482 pos += bytes; 1483 buf += bytes; 1484 if (pos > inode->i_size) 1485 i_size_write(inode, pos); 1486 1487 flush_dcache_page(page); 1488 set_page_dirty(page); 1489 mark_page_accessed(page); 1490 page_cache_release(page); 1491 1492 if (left) { 1493 pos -= left; 1494 written -= left; 1495 err = -EFAULT; 1496 break; 1497 } 1498 1499 /* 1500 * Our dirty pages are not counted in nr_dirty, 1501 * and we do not attempt to balance dirty pages. 1502 */ 1503 1504 cond_resched(); 1505 } while (count); 1506 1507 *ppos = pos; 1508 if (written) 1509 err = written; 1510out: 1511 mutex_unlock(&inode->i_mutex); 1512 return err; 1513} 1514 1515static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1516{ 1517 struct inode *inode = filp->f_dentry->d_inode; 1518 struct address_space *mapping = inode->i_mapping; 1519 unsigned long index, offset; 1520 1521 index = *ppos >> PAGE_CACHE_SHIFT; 1522 offset = *ppos & ~PAGE_CACHE_MASK; 1523 1524 for (;;) { 1525 struct page *page = NULL; 1526 unsigned long end_index, nr, ret; 1527 loff_t i_size = i_size_read(inode); 1528 1529 end_index = i_size >> PAGE_CACHE_SHIFT; 1530 if (index > end_index) 1531 break; 1532 if (index == end_index) { 1533 nr = i_size & ~PAGE_CACHE_MASK; 1534 if (nr <= offset) 1535 break; 1536 } 1537 1538 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL); 1539 if (desc->error) { 1540 if (desc->error == -EINVAL) 1541 desc->error = 0; 1542 break; 1543 } 1544 1545 /* 1546 * We must evaluate after, since reads (unlike writes) 1547 * are called without i_mutex protection against truncate 1548 */ 1549 nr = PAGE_CACHE_SIZE; 1550 i_size = i_size_read(inode); 1551 end_index = i_size >> PAGE_CACHE_SHIFT; 1552 if (index == end_index) { 1553 nr = i_size & ~PAGE_CACHE_MASK; 1554 if (nr <= offset) { 1555 if (page) 1556 page_cache_release(page); 1557 break; 1558 } 1559 } 1560 nr -= offset; 1561 1562 if (page) { 1563 /* 1564 * If users can be writing to this page using arbitrary 1565 * virtual addresses, take care about potential aliasing 1566 * before reading the page on the kernel side. 1567 */ 1568 if (mapping_writably_mapped(mapping)) 1569 flush_dcache_page(page); 1570 /* 1571 * Mark the page accessed if we read the beginning. 1572 */ 1573 if (!offset) 1574 mark_page_accessed(page); 1575 } else { 1576 page = ZERO_PAGE(0); 1577 page_cache_get(page); 1578 } 1579 1580 /* 1581 * Ok, we have the page, and it's up-to-date, so 1582 * now we can copy it to user space... 1583 * 1584 * The actor routine returns how many bytes were actually used.. 1585 * NOTE! This may not be the same as how much of a user buffer 1586 * we filled up (we may be padding etc), so we can only update 1587 * "pos" here (the actor routine has to update the user buffer 1588 * pointers and the remaining count). 1589 */ 1590 ret = actor(desc, page, offset, nr); 1591 offset += ret; 1592 index += offset >> PAGE_CACHE_SHIFT; 1593 offset &= ~PAGE_CACHE_MASK; 1594 1595 page_cache_release(page); 1596 if (ret != nr || !desc->count) 1597 break; 1598 1599 cond_resched(); 1600 } 1601 1602 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1603 file_accessed(filp); 1604} 1605 1606static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1607{ 1608 read_descriptor_t desc; 1609 1610 if ((ssize_t) count < 0) 1611 return -EINVAL; 1612 if (!access_ok(VERIFY_WRITE, buf, count)) 1613 return -EFAULT; 1614 if (!count) 1615 return 0; 1616 1617 desc.written = 0; 1618 desc.count = count; 1619 desc.arg.buf = buf; 1620 desc.error = 0; 1621 1622 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1623 if (desc.written) 1624 return desc.written; 1625 return desc.error; 1626} 1627 1628static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos, 1629 size_t count, read_actor_t actor, void *target) 1630{ 1631 read_descriptor_t desc; 1632 1633 if (!count) 1634 return 0; 1635 1636 desc.written = 0; 1637 desc.count = count; 1638 desc.arg.data = target; 1639 desc.error = 0; 1640 1641 do_shmem_file_read(in_file, ppos, &desc, actor); 1642 if (desc.written) 1643 return desc.written; 1644 return desc.error; 1645} 1646 1647static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1648{ 1649 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1650 1651 buf->f_type = TMPFS_MAGIC; 1652 buf->f_bsize = PAGE_CACHE_SIZE; 1653 buf->f_namelen = NAME_MAX; 1654 spin_lock(&sbinfo->stat_lock); 1655 if (sbinfo->max_blocks) { 1656 buf->f_blocks = sbinfo->max_blocks; 1657 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1658 } 1659 if (sbinfo->max_inodes) { 1660 buf->f_files = sbinfo->max_inodes; 1661 buf->f_ffree = sbinfo->free_inodes; 1662 } 1663 /* else leave those fields 0 like simple_statfs */ 1664 spin_unlock(&sbinfo->stat_lock); 1665 return 0; 1666} 1667 1668/* 1669 * File creation. Allocate an inode, and we're done.. 1670 */ 1671static int 1672shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1673{ 1674 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1675 int error = -ENOSPC; 1676 1677 if (inode) { 1678 error = security_inode_init_security(inode, dir, NULL, NULL, 1679 NULL); 1680 if (error) { 1681 if (error != -EOPNOTSUPP) { 1682 iput(inode); 1683 return error; 1684 } 1685 error = 0; 1686 } 1687 if (dir->i_mode & S_ISGID) { 1688 inode->i_gid = dir->i_gid; 1689 if (S_ISDIR(mode)) 1690 inode->i_mode |= S_ISGID; 1691 } 1692 dir->i_size += BOGO_DIRENT_SIZE; 1693 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1694 d_instantiate(dentry, inode); 1695 dget(dentry); /* Extra count - pin the dentry in core */ 1696 } 1697 return error; 1698} 1699 1700static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1701{ 1702 int error; 1703 1704 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1705 return error; 1706 dir->i_nlink++; 1707 return 0; 1708} 1709 1710static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1711 struct nameidata *nd) 1712{ 1713 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1714} 1715 1716/* 1717 * Link a file.. 1718 */ 1719static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1720{ 1721 struct inode *inode = old_dentry->d_inode; 1722 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1723 1724 /* 1725 * No ordinary (disk based) filesystem counts links as inodes; 1726 * but each new link needs a new dentry, pinning lowmem, and 1727 * tmpfs dentries cannot be pruned until they are unlinked. 1728 */ 1729 if (sbinfo->max_inodes) { 1730 spin_lock(&sbinfo->stat_lock); 1731 if (!sbinfo->free_inodes) { 1732 spin_unlock(&sbinfo->stat_lock); 1733 return -ENOSPC; 1734 } 1735 sbinfo->free_inodes--; 1736 spin_unlock(&sbinfo->stat_lock); 1737 } 1738 1739 dir->i_size += BOGO_DIRENT_SIZE; 1740 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1741 inode->i_nlink++; 1742 atomic_inc(&inode->i_count); /* New dentry reference */ 1743 dget(dentry); /* Extra pinning count for the created dentry */ 1744 d_instantiate(dentry, inode); 1745 return 0; 1746} 1747 1748static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1749{ 1750 struct inode *inode = dentry->d_inode; 1751 1752 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) { 1753 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1754 if (sbinfo->max_inodes) { 1755 spin_lock(&sbinfo->stat_lock); 1756 sbinfo->free_inodes++; 1757 spin_unlock(&sbinfo->stat_lock); 1758 } 1759 } 1760 1761 dir->i_size -= BOGO_DIRENT_SIZE; 1762 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1763 inode->i_nlink--; 1764 dput(dentry); /* Undo the count from "create" - this does all the work */ 1765 return 0; 1766} 1767 1768static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1769{ 1770 if (!simple_empty(dentry)) 1771 return -ENOTEMPTY; 1772 1773 dentry->d_inode->i_nlink--; 1774 dir->i_nlink--; 1775 return shmem_unlink(dir, dentry); 1776} 1777 1778/* 1779 * The VFS layer already does all the dentry stuff for rename, 1780 * we just have to decrement the usage count for the target if 1781 * it exists so that the VFS layer correctly free's it when it 1782 * gets overwritten. 1783 */ 1784static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1785{ 1786 struct inode *inode = old_dentry->d_inode; 1787 int they_are_dirs = S_ISDIR(inode->i_mode); 1788 1789 if (!simple_empty(new_dentry)) 1790 return -ENOTEMPTY; 1791 1792 if (new_dentry->d_inode) { 1793 (void) shmem_unlink(new_dir, new_dentry); 1794 if (they_are_dirs) 1795 old_dir->i_nlink--; 1796 } else if (they_are_dirs) { 1797 old_dir->i_nlink--; 1798 new_dir->i_nlink++; 1799 } 1800 1801 old_dir->i_size -= BOGO_DIRENT_SIZE; 1802 new_dir->i_size += BOGO_DIRENT_SIZE; 1803 old_dir->i_ctime = old_dir->i_mtime = 1804 new_dir->i_ctime = new_dir->i_mtime = 1805 inode->i_ctime = CURRENT_TIME; 1806 return 0; 1807} 1808 1809static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1810{ 1811 int error; 1812 int len; 1813 struct inode *inode; 1814 struct page *page = NULL; 1815 char *kaddr; 1816 struct shmem_inode_info *info; 1817 1818 len = strlen(symname) + 1; 1819 if (len > PAGE_CACHE_SIZE) 1820 return -ENAMETOOLONG; 1821 1822 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1823 if (!inode) 1824 return -ENOSPC; 1825 1826 error = security_inode_init_security(inode, dir, NULL, NULL, 1827 NULL); 1828 if (error) { 1829 if (error != -EOPNOTSUPP) { 1830 iput(inode); 1831 return error; 1832 } 1833 error = 0; 1834 } 1835 1836 info = SHMEM_I(inode); 1837 inode->i_size = len-1; 1838 if (len <= (char *)inode - (char *)info) { 1839 /* do it inline */ 1840 memcpy(info, symname, len); 1841 inode->i_op = &shmem_symlink_inline_operations; 1842 } else { 1843 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1844 if (error) { 1845 iput(inode); 1846 return error; 1847 } 1848 inode->i_op = &shmem_symlink_inode_operations; 1849 kaddr = kmap_atomic(page, KM_USER0); 1850 memcpy(kaddr, symname, len); 1851 kunmap_atomic(kaddr, KM_USER0); 1852 set_page_dirty(page); 1853 page_cache_release(page); 1854 } 1855 if (dir->i_mode & S_ISGID) 1856 inode->i_gid = dir->i_gid; 1857 dir->i_size += BOGO_DIRENT_SIZE; 1858 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1859 d_instantiate(dentry, inode); 1860 dget(dentry); 1861 return 0; 1862} 1863 1864static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1865{ 1866 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1867 return NULL; 1868} 1869 1870static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1871{ 1872 struct page *page = NULL; 1873 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1874 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1875 return page; 1876} 1877 1878static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1879{ 1880 if (!IS_ERR(nd_get_link(nd))) { 1881 struct page *page = cookie; 1882 kunmap(page); 1883 mark_page_accessed(page); 1884 page_cache_release(page); 1885 } 1886} 1887 1888static struct inode_operations shmem_symlink_inline_operations = { 1889 .readlink = generic_readlink, 1890 .follow_link = shmem_follow_link_inline, 1891}; 1892 1893static struct inode_operations shmem_symlink_inode_operations = { 1894 .truncate = shmem_truncate, 1895 .readlink = generic_readlink, 1896 .follow_link = shmem_follow_link, 1897 .put_link = shmem_put_link, 1898}; 1899 1900static int shmem_parse_options(char *options, int *mode, uid_t *uid, 1901 gid_t *gid, unsigned long *blocks, unsigned long *inodes, 1902 int *policy, nodemask_t *policy_nodes) 1903{ 1904 char *this_char, *value, *rest; 1905 1906 while (options != NULL) { 1907 this_char = options; 1908 for (;;) { 1909 /* 1910 * NUL-terminate this option: unfortunately, 1911 * mount options form a comma-separated list, 1912 * but mpol's nodelist may also contain commas. 1913 */ 1914 options = strchr(options, ','); 1915 if (options == NULL) 1916 break; 1917 options++; 1918 if (!isdigit(*options)) { 1919 options[-1] = '\0'; 1920 break; 1921 } 1922 } 1923 if (!*this_char) 1924 continue; 1925 if ((value = strchr(this_char,'=')) != NULL) { 1926 *value++ = 0; 1927 } else { 1928 printk(KERN_ERR 1929 "tmpfs: No value for mount option '%s'\n", 1930 this_char); 1931 return 1; 1932 } 1933 1934 if (!strcmp(this_char,"size")) { 1935 unsigned long long size; 1936 size = memparse(value,&rest); 1937 if (*rest == '%') { 1938 size <<= PAGE_SHIFT; 1939 size *= totalram_pages; 1940 do_div(size, 100); 1941 rest++; 1942 } 1943 if (*rest) 1944 goto bad_val; 1945 *blocks = size >> PAGE_CACHE_SHIFT; 1946 } else if (!strcmp(this_char,"nr_blocks")) { 1947 *blocks = memparse(value,&rest); 1948 if (*rest) 1949 goto bad_val; 1950 } else if (!strcmp(this_char,"nr_inodes")) { 1951 *inodes = memparse(value,&rest); 1952 if (*rest) 1953 goto bad_val; 1954 } else if (!strcmp(this_char,"mode")) { 1955 if (!mode) 1956 continue; 1957 *mode = simple_strtoul(value,&rest,8); 1958 if (*rest) 1959 goto bad_val; 1960 } else if (!strcmp(this_char,"uid")) { 1961 if (!uid) 1962 continue; 1963 *uid = simple_strtoul(value,&rest,0); 1964 if (*rest) 1965 goto bad_val; 1966 } else if (!strcmp(this_char,"gid")) { 1967 if (!gid) 1968 continue; 1969 *gid = simple_strtoul(value,&rest,0); 1970 if (*rest) 1971 goto bad_val; 1972 } else if (!strcmp(this_char,"mpol")) { 1973 if (shmem_parse_mpol(value,policy,policy_nodes)) 1974 goto bad_val; 1975 } else { 1976 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 1977 this_char); 1978 return 1; 1979 } 1980 } 1981 return 0; 1982 1983bad_val: 1984 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 1985 value, this_char); 1986 return 1; 1987 1988} 1989 1990static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 1991{ 1992 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1993 unsigned long max_blocks = sbinfo->max_blocks; 1994 unsigned long max_inodes = sbinfo->max_inodes; 1995 int policy = sbinfo->policy; 1996 nodemask_t policy_nodes = sbinfo->policy_nodes; 1997 unsigned long blocks; 1998 unsigned long inodes; 1999 int error = -EINVAL; 2000 2001 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, 2002 &max_inodes, &policy, &policy_nodes)) 2003 return error; 2004 2005 spin_lock(&sbinfo->stat_lock); 2006 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2007 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2008 if (max_blocks < blocks) 2009 goto out; 2010 if (max_inodes < inodes) 2011 goto out; 2012 /* 2013 * Those tests also disallow limited->unlimited while any are in 2014 * use, so i_blocks will always be zero when max_blocks is zero; 2015 * but we must separately disallow unlimited->limited, because 2016 * in that case we have no record of how much is already in use. 2017 */ 2018 if (max_blocks && !sbinfo->max_blocks) 2019 goto out; 2020 if (max_inodes && !sbinfo->max_inodes) 2021 goto out; 2022 2023 error = 0; 2024 sbinfo->max_blocks = max_blocks; 2025 sbinfo->free_blocks = max_blocks - blocks; 2026 sbinfo->max_inodes = max_inodes; 2027 sbinfo->free_inodes = max_inodes - inodes; 2028 sbinfo->policy = policy; 2029 sbinfo->policy_nodes = policy_nodes; 2030out: 2031 spin_unlock(&sbinfo->stat_lock); 2032 return error; 2033} 2034#endif 2035 2036static void shmem_put_super(struct super_block *sb) 2037{ 2038 kfree(sb->s_fs_info); 2039 sb->s_fs_info = NULL; 2040} 2041 2042static int shmem_fill_super(struct super_block *sb, 2043 void *data, int silent) 2044{ 2045 struct inode *inode; 2046 struct dentry *root; 2047 int mode = S_IRWXUGO | S_ISVTX; 2048 uid_t uid = current->fsuid; 2049 gid_t gid = current->fsgid; 2050 int err = -ENOMEM; 2051 struct shmem_sb_info *sbinfo; 2052 unsigned long blocks = 0; 2053 unsigned long inodes = 0; 2054 int policy = MPOL_DEFAULT; 2055 nodemask_t policy_nodes = node_online_map; 2056 2057#ifdef CONFIG_TMPFS 2058 /* 2059 * Per default we only allow half of the physical ram per 2060 * tmpfs instance, limiting inodes to one per page of lowmem; 2061 * but the internal instance is left unlimited. 2062 */ 2063 if (!(sb->s_flags & MS_NOUSER)) { 2064 blocks = totalram_pages / 2; 2065 inodes = totalram_pages - totalhigh_pages; 2066 if (inodes > blocks) 2067 inodes = blocks; 2068 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, 2069 &inodes, &policy, &policy_nodes)) 2070 return -EINVAL; 2071 } 2072#else 2073 sb->s_flags |= MS_NOUSER; 2074#endif 2075 2076 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2077 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 2078 L1_CACHE_BYTES), GFP_KERNEL); 2079 if (!sbinfo) 2080 return -ENOMEM; 2081 2082 spin_lock_init(&sbinfo->stat_lock); 2083 sbinfo->max_blocks = blocks; 2084 sbinfo->free_blocks = blocks; 2085 sbinfo->max_inodes = inodes; 2086 sbinfo->free_inodes = inodes; 2087 sbinfo->policy = policy; 2088 sbinfo->policy_nodes = policy_nodes; 2089 2090 sb->s_fs_info = sbinfo; 2091 sb->s_maxbytes = SHMEM_MAX_BYTES; 2092 sb->s_blocksize = PAGE_CACHE_SIZE; 2093 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2094 sb->s_magic = TMPFS_MAGIC; 2095 sb->s_op = &shmem_ops; 2096 sb->s_time_gran = 1; 2097 2098 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 2099 if (!inode) 2100 goto failed; 2101 inode->i_uid = uid; 2102 inode->i_gid = gid; 2103 root = d_alloc_root(inode); 2104 if (!root) 2105 goto failed_iput; 2106 sb->s_root = root; 2107 return 0; 2108 2109failed_iput: 2110 iput(inode); 2111failed: 2112 shmem_put_super(sb); 2113 return err; 2114} 2115 2116static struct kmem_cache *shmem_inode_cachep; 2117 2118static struct inode *shmem_alloc_inode(struct super_block *sb) 2119{ 2120 struct shmem_inode_info *p; 2121 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL); 2122 if (!p) 2123 return NULL; 2124 return &p->vfs_inode; 2125} 2126 2127static void shmem_destroy_inode(struct inode *inode) 2128{ 2129 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2130 /* only struct inode is valid if it's an inline symlink */ 2131 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2132 } 2133 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2134} 2135 2136static void init_once(void *foo, struct kmem_cache *cachep, 2137 unsigned long flags) 2138{ 2139 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2140 2141 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == 2142 SLAB_CTOR_CONSTRUCTOR) { 2143 inode_init_once(&p->vfs_inode); 2144 } 2145} 2146 2147static int init_inodecache(void) 2148{ 2149 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2150 sizeof(struct shmem_inode_info), 2151 0, 0, init_once, NULL); 2152 if (shmem_inode_cachep == NULL) 2153 return -ENOMEM; 2154 return 0; 2155} 2156 2157static void destroy_inodecache(void) 2158{ 2159 kmem_cache_destroy(shmem_inode_cachep); 2160} 2161 2162static const struct address_space_operations shmem_aops = { 2163 .writepage = shmem_writepage, 2164 .set_page_dirty = __set_page_dirty_nobuffers, 2165#ifdef CONFIG_TMPFS 2166 .prepare_write = shmem_prepare_write, 2167 .commit_write = simple_commit_write, 2168#endif 2169 .migratepage = migrate_page, 2170}; 2171 2172static struct file_operations shmem_file_operations = { 2173 .mmap = shmem_mmap, 2174#ifdef CONFIG_TMPFS 2175 .llseek = generic_file_llseek, 2176 .read = shmem_file_read, 2177 .write = shmem_file_write, 2178 .fsync = simple_sync_file, 2179 .sendfile = shmem_file_sendfile, 2180#endif 2181}; 2182 2183static struct inode_operations shmem_inode_operations = { 2184 .truncate = shmem_truncate, 2185 .setattr = shmem_notify_change, 2186 .truncate_range = shmem_truncate_range, 2187}; 2188 2189static struct inode_operations shmem_dir_inode_operations = { 2190#ifdef CONFIG_TMPFS 2191 .create = shmem_create, 2192 .lookup = simple_lookup, 2193 .link = shmem_link, 2194 .unlink = shmem_unlink, 2195 .symlink = shmem_symlink, 2196 .mkdir = shmem_mkdir, 2197 .rmdir = shmem_rmdir, 2198 .mknod = shmem_mknod, 2199 .rename = shmem_rename, 2200#endif 2201}; 2202 2203static struct super_operations shmem_ops = { 2204 .alloc_inode = shmem_alloc_inode, 2205 .destroy_inode = shmem_destroy_inode, 2206#ifdef CONFIG_TMPFS 2207 .statfs = shmem_statfs, 2208 .remount_fs = shmem_remount_fs, 2209#endif 2210 .delete_inode = shmem_delete_inode, 2211 .drop_inode = generic_delete_inode, 2212 .put_super = shmem_put_super, 2213}; 2214 2215static struct vm_operations_struct shmem_vm_ops = { 2216 .nopage = shmem_nopage, 2217 .populate = shmem_populate, 2218#ifdef CONFIG_NUMA 2219 .set_policy = shmem_set_policy, 2220 .get_policy = shmem_get_policy, 2221#endif 2222}; 2223 2224 2225static int shmem_get_sb(struct file_system_type *fs_type, 2226 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2227{ 2228 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2229} 2230 2231static struct file_system_type tmpfs_fs_type = { 2232 .owner = THIS_MODULE, 2233 .name = "tmpfs", 2234 .get_sb = shmem_get_sb, 2235 .kill_sb = kill_litter_super, 2236}; 2237static struct vfsmount *shm_mnt; 2238 2239static int __init init_tmpfs(void) 2240{ 2241 int error; 2242 2243 error = init_inodecache(); 2244 if (error) 2245 goto out3; 2246 2247 error = register_filesystem(&tmpfs_fs_type); 2248 if (error) { 2249 printk(KERN_ERR "Could not register tmpfs\n"); 2250 goto out2; 2251 } 2252 2253 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2254 tmpfs_fs_type.name, NULL); 2255 if (IS_ERR(shm_mnt)) { 2256 error = PTR_ERR(shm_mnt); 2257 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2258 goto out1; 2259 } 2260 return 0; 2261 2262out1: 2263 unregister_filesystem(&tmpfs_fs_type); 2264out2: 2265 destroy_inodecache(); 2266out3: 2267 shm_mnt = ERR_PTR(error); 2268 return error; 2269} 2270module_init(init_tmpfs) 2271 2272/* 2273 * shmem_file_setup - get an unlinked file living in tmpfs 2274 * 2275 * @name: name for dentry (to be seen in /proc/<pid>/maps 2276 * @size: size to be set for the file 2277 * 2278 */ 2279struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2280{ 2281 int error; 2282 struct file *file; 2283 struct inode *inode; 2284 struct dentry *dentry, *root; 2285 struct qstr this; 2286 2287 if (IS_ERR(shm_mnt)) 2288 return (void *)shm_mnt; 2289 2290 if (size < 0 || size > SHMEM_MAX_BYTES) 2291 return ERR_PTR(-EINVAL); 2292 2293 if (shmem_acct_size(flags, size)) 2294 return ERR_PTR(-ENOMEM); 2295 2296 error = -ENOMEM; 2297 this.name = name; 2298 this.len = strlen(name); 2299 this.hash = 0; /* will go */ 2300 root = shm_mnt->mnt_root; 2301 dentry = d_alloc(root, &this); 2302 if (!dentry) 2303 goto put_memory; 2304 2305 error = -ENFILE; 2306 file = get_empty_filp(); 2307 if (!file) 2308 goto put_dentry; 2309 2310 error = -ENOSPC; 2311 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2312 if (!inode) 2313 goto close_file; 2314 2315 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2316 d_instantiate(dentry, inode); 2317 inode->i_size = size; 2318 inode->i_nlink = 0; /* It is unlinked */ 2319 file->f_vfsmnt = mntget(shm_mnt); 2320 file->f_dentry = dentry; 2321 file->f_mapping = inode->i_mapping; 2322 file->f_op = &shmem_file_operations; 2323 file->f_mode = FMODE_WRITE | FMODE_READ; 2324 return file; 2325 2326close_file: 2327 put_filp(file); 2328put_dentry: 2329 dput(dentry); 2330put_memory: 2331 shmem_unacct_size(flags, size); 2332 return ERR_PTR(error); 2333} 2334 2335/* 2336 * shmem_zero_setup - setup a shared anonymous mapping 2337 * 2338 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2339 */ 2340int shmem_zero_setup(struct vm_area_struct *vma) 2341{ 2342 struct file *file; 2343 loff_t size = vma->vm_end - vma->vm_start; 2344 2345 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2346 if (IS_ERR(file)) 2347 return PTR_ERR(file); 2348 2349 if (vma->vm_file) 2350 fput(vma->vm_file); 2351 vma->vm_file = file; 2352 vma->vm_ops = &shmem_vm_ops; 2353 return 0; 2354} 2355