shmem.c revision 92a3d03aab912624cae799e5772a6eb2ef55083f
1/* 2 * Resizable virtual memory filesystem for Linux. 3 * 4 * Copyright (C) 2000 Linus Torvalds. 5 * 2000 Transmeta Corp. 6 * 2000-2001 Christoph Rohland 7 * 2000-2001 SAP AG 8 * 2002 Red Hat Inc. 9 * Copyright (C) 2002-2005 Hugh Dickins. 10 * Copyright (C) 2002-2005 VERITAS Software Corporation. 11 * Copyright (C) 2004 Andi Kleen, SuSE Labs 12 * 13 * Extended attribute support for tmpfs: 14 * Copyright (c) 2004, Luke Kenneth Casson Leighton <lkcl@lkcl.net> 15 * Copyright (c) 2004 Red Hat, Inc., James Morris <jmorris@redhat.com> 16 * 17 * This file is released under the GPL. 18 */ 19 20/* 21 * This virtual memory filesystem is heavily based on the ramfs. It 22 * extends ramfs by the ability to use swap and honor resource limits 23 * which makes it a completely usable filesystem. 24 */ 25 26#include <linux/module.h> 27#include <linux/init.h> 28#include <linux/fs.h> 29#include <linux/xattr.h> 30#include <linux/generic_acl.h> 31#include <linux/mm.h> 32#include <linux/mman.h> 33#include <linux/file.h> 34#include <linux/swap.h> 35#include <linux/pagemap.h> 36#include <linux/string.h> 37#include <linux/slab.h> 38#include <linux/backing-dev.h> 39#include <linux/shmem_fs.h> 40#include <linux/mount.h> 41#include <linux/writeback.h> 42#include <linux/vfs.h> 43#include <linux/blkdev.h> 44#include <linux/security.h> 45#include <linux/swapops.h> 46#include <linux/mempolicy.h> 47#include <linux/namei.h> 48#include <linux/ctype.h> 49#include <linux/migrate.h> 50#include <linux/highmem.h> 51#include <linux/backing-dev.h> 52 53#include <asm/uaccess.h> 54#include <asm/div64.h> 55#include <asm/pgtable.h> 56 57/* This magic number is used in glibc for posix shared memory */ 58#define TMPFS_MAGIC 0x01021994 59 60#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) 61#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) 62#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) 63 64#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) 65#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT) 66 67#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) 68 69/* info->flags needs VM_flags to handle pagein/truncate races efficiently */ 70#define SHMEM_PAGEIN VM_READ 71#define SHMEM_TRUNCATE VM_WRITE 72 73/* Definition to limit shmem_truncate's steps between cond_rescheds */ 74#define LATENCY_LIMIT 64 75 76/* Pretend that each entry is of this size in directory's i_size */ 77#define BOGO_DIRENT_SIZE 20 78 79/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ 80enum sgp_type { 81 SGP_QUICK, /* don't try more than file page cache lookup */ 82 SGP_READ, /* don't exceed i_size, don't allocate page */ 83 SGP_CACHE, /* don't exceed i_size, may allocate page */ 84 SGP_WRITE, /* may exceed i_size, may allocate page */ 85}; 86 87static int shmem_getpage(struct inode *inode, unsigned long idx, 88 struct page **pagep, enum sgp_type sgp, int *type); 89 90static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) 91{ 92 /* 93 * The above definition of ENTRIES_PER_PAGE, and the use of 94 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 95 * might be reconsidered if it ever diverges from PAGE_SIZE. 96 */ 97 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT); 98} 99 100static inline void shmem_dir_free(struct page *page) 101{ 102 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 103} 104 105static struct page **shmem_dir_map(struct page *page) 106{ 107 return (struct page **)kmap_atomic(page, KM_USER0); 108} 109 110static inline void shmem_dir_unmap(struct page **dir) 111{ 112 kunmap_atomic(dir, KM_USER0); 113} 114 115static swp_entry_t *shmem_swp_map(struct page *page) 116{ 117 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 118} 119 120static inline void shmem_swp_balance_unmap(void) 121{ 122 /* 123 * When passing a pointer to an i_direct entry, to code which 124 * also handles indirect entries and so will shmem_swp_unmap, 125 * we must arrange for the preempt count to remain in balance. 126 * What kmap_atomic of a lowmem page does depends on config 127 * and architecture, so pretend to kmap_atomic some lowmem page. 128 */ 129 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 130} 131 132static inline void shmem_swp_unmap(swp_entry_t *entry) 133{ 134 kunmap_atomic(entry, KM_USER1); 135} 136 137static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 138{ 139 return sb->s_fs_info; 140} 141 142/* 143 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 144 * for shared memory and for shared anonymous (/dev/zero) mappings 145 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 146 * consistent with the pre-accounting of private mappings ... 147 */ 148static inline int shmem_acct_size(unsigned long flags, loff_t size) 149{ 150 return (flags & VM_ACCOUNT)? 151 security_vm_enough_memory(VM_ACCT(size)): 0; 152} 153 154static inline void shmem_unacct_size(unsigned long flags, loff_t size) 155{ 156 if (flags & VM_ACCOUNT) 157 vm_unacct_memory(VM_ACCT(size)); 158} 159 160/* 161 * ... whereas tmpfs objects are accounted incrementally as 162 * pages are allocated, in order to allow huge sparse files. 163 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 164 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 165 */ 166static inline int shmem_acct_block(unsigned long flags) 167{ 168 return (flags & VM_ACCOUNT)? 169 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE)); 170} 171 172static inline void shmem_unacct_blocks(unsigned long flags, long pages) 173{ 174 if (!(flags & VM_ACCOUNT)) 175 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 176} 177 178static struct super_operations shmem_ops; 179static const struct address_space_operations shmem_aops; 180static const struct file_operations shmem_file_operations; 181static struct inode_operations shmem_inode_operations; 182static struct inode_operations shmem_dir_inode_operations; 183static struct inode_operations shmem_special_inode_operations; 184static struct vm_operations_struct shmem_vm_ops; 185 186static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 187 .ra_pages = 0, /* No readahead */ 188 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, 189 .unplug_io_fn = default_unplug_io_fn, 190}; 191 192static LIST_HEAD(shmem_swaplist); 193static DEFINE_SPINLOCK(shmem_swaplist_lock); 194 195static void shmem_free_blocks(struct inode *inode, long pages) 196{ 197 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 198 if (sbinfo->max_blocks) { 199 spin_lock(&sbinfo->stat_lock); 200 sbinfo->free_blocks += pages; 201 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 202 spin_unlock(&sbinfo->stat_lock); 203 } 204} 205 206/* 207 * shmem_recalc_inode - recalculate the size of an inode 208 * 209 * @inode: inode to recalc 210 * 211 * We have to calculate the free blocks since the mm can drop 212 * undirtied hole pages behind our back. 213 * 214 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 215 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 216 * 217 * It has to be called with the spinlock held. 218 */ 219static void shmem_recalc_inode(struct inode *inode) 220{ 221 struct shmem_inode_info *info = SHMEM_I(inode); 222 long freed; 223 224 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 225 if (freed > 0) { 226 info->alloced -= freed; 227 shmem_unacct_blocks(info->flags, freed); 228 shmem_free_blocks(inode, freed); 229 } 230} 231 232/* 233 * shmem_swp_entry - find the swap vector position in the info structure 234 * 235 * @info: info structure for the inode 236 * @index: index of the page to find 237 * @page: optional page to add to the structure. Has to be preset to 238 * all zeros 239 * 240 * If there is no space allocated yet it will return NULL when 241 * page is NULL, else it will use the page for the needed block, 242 * setting it to NULL on return to indicate that it has been used. 243 * 244 * The swap vector is organized the following way: 245 * 246 * There are SHMEM_NR_DIRECT entries directly stored in the 247 * shmem_inode_info structure. So small files do not need an addional 248 * allocation. 249 * 250 * For pages with index > SHMEM_NR_DIRECT there is the pointer 251 * i_indirect which points to a page which holds in the first half 252 * doubly indirect blocks, in the second half triple indirect blocks: 253 * 254 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 255 * following layout (for SHMEM_NR_DIRECT == 16): 256 * 257 * i_indirect -> dir --> 16-19 258 * | +-> 20-23 259 * | 260 * +-->dir2 --> 24-27 261 * | +-> 28-31 262 * | +-> 32-35 263 * | +-> 36-39 264 * | 265 * +-->dir3 --> 40-43 266 * +-> 44-47 267 * +-> 48-51 268 * +-> 52-55 269 */ 270static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 271{ 272 unsigned long offset; 273 struct page **dir; 274 struct page *subdir; 275 276 if (index < SHMEM_NR_DIRECT) { 277 shmem_swp_balance_unmap(); 278 return info->i_direct+index; 279 } 280 if (!info->i_indirect) { 281 if (page) { 282 info->i_indirect = *page; 283 *page = NULL; 284 } 285 return NULL; /* need another page */ 286 } 287 288 index -= SHMEM_NR_DIRECT; 289 offset = index % ENTRIES_PER_PAGE; 290 index /= ENTRIES_PER_PAGE; 291 dir = shmem_dir_map(info->i_indirect); 292 293 if (index >= ENTRIES_PER_PAGE/2) { 294 index -= ENTRIES_PER_PAGE/2; 295 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 296 index %= ENTRIES_PER_PAGE; 297 subdir = *dir; 298 if (!subdir) { 299 if (page) { 300 *dir = *page; 301 *page = NULL; 302 } 303 shmem_dir_unmap(dir); 304 return NULL; /* need another page */ 305 } 306 shmem_dir_unmap(dir); 307 dir = shmem_dir_map(subdir); 308 } 309 310 dir += index; 311 subdir = *dir; 312 if (!subdir) { 313 if (!page || !(subdir = *page)) { 314 shmem_dir_unmap(dir); 315 return NULL; /* need a page */ 316 } 317 *dir = subdir; 318 *page = NULL; 319 } 320 shmem_dir_unmap(dir); 321 return shmem_swp_map(subdir) + offset; 322} 323 324static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 325{ 326 long incdec = value? 1: -1; 327 328 entry->val = value; 329 info->swapped += incdec; 330 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { 331 struct page *page = kmap_atomic_to_page(entry); 332 set_page_private(page, page_private(page) + incdec); 333 } 334} 335 336/* 337 * shmem_swp_alloc - get the position of the swap entry for the page. 338 * If it does not exist allocate the entry. 339 * 340 * @info: info structure for the inode 341 * @index: index of the page to find 342 * @sgp: check and recheck i_size? skip allocation? 343 */ 344static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 345{ 346 struct inode *inode = &info->vfs_inode; 347 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 348 struct page *page = NULL; 349 swp_entry_t *entry; 350 351 if (sgp != SGP_WRITE && 352 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 353 return ERR_PTR(-EINVAL); 354 355 while (!(entry = shmem_swp_entry(info, index, &page))) { 356 if (sgp == SGP_READ) 357 return shmem_swp_map(ZERO_PAGE(0)); 358 /* 359 * Test free_blocks against 1 not 0, since we have 1 data 360 * page (and perhaps indirect index pages) yet to allocate: 361 * a waste to allocate index if we cannot allocate data. 362 */ 363 if (sbinfo->max_blocks) { 364 spin_lock(&sbinfo->stat_lock); 365 if (sbinfo->free_blocks <= 1) { 366 spin_unlock(&sbinfo->stat_lock); 367 return ERR_PTR(-ENOSPC); 368 } 369 sbinfo->free_blocks--; 370 inode->i_blocks += BLOCKS_PER_PAGE; 371 spin_unlock(&sbinfo->stat_lock); 372 } 373 374 spin_unlock(&info->lock); 375 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO); 376 if (page) 377 set_page_private(page, 0); 378 spin_lock(&info->lock); 379 380 if (!page) { 381 shmem_free_blocks(inode, 1); 382 return ERR_PTR(-ENOMEM); 383 } 384 if (sgp != SGP_WRITE && 385 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 386 entry = ERR_PTR(-EINVAL); 387 break; 388 } 389 if (info->next_index <= index) 390 info->next_index = index + 1; 391 } 392 if (page) { 393 /* another task gave its page, or truncated the file */ 394 shmem_free_blocks(inode, 1); 395 shmem_dir_free(page); 396 } 397 if (info->next_index <= index && !IS_ERR(entry)) 398 info->next_index = index + 1; 399 return entry; 400} 401 402/* 403 * shmem_free_swp - free some swap entries in a directory 404 * 405 * @dir: pointer to the directory 406 * @edir: pointer after last entry of the directory 407 */ 408static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir) 409{ 410 swp_entry_t *ptr; 411 int freed = 0; 412 413 for (ptr = dir; ptr < edir; ptr++) { 414 if (ptr->val) { 415 free_swap_and_cache(*ptr); 416 *ptr = (swp_entry_t){0}; 417 freed++; 418 } 419 } 420 return freed; 421} 422 423static int shmem_map_and_free_swp(struct page *subdir, 424 int offset, int limit, struct page ***dir) 425{ 426 swp_entry_t *ptr; 427 int freed = 0; 428 429 ptr = shmem_swp_map(subdir); 430 for (; offset < limit; offset += LATENCY_LIMIT) { 431 int size = limit - offset; 432 if (size > LATENCY_LIMIT) 433 size = LATENCY_LIMIT; 434 freed += shmem_free_swp(ptr+offset, ptr+offset+size); 435 if (need_resched()) { 436 shmem_swp_unmap(ptr); 437 if (*dir) { 438 shmem_dir_unmap(*dir); 439 *dir = NULL; 440 } 441 cond_resched(); 442 ptr = shmem_swp_map(subdir); 443 } 444 } 445 shmem_swp_unmap(ptr); 446 return freed; 447} 448 449static void shmem_free_pages(struct list_head *next) 450{ 451 struct page *page; 452 int freed = 0; 453 454 do { 455 page = container_of(next, struct page, lru); 456 next = next->next; 457 shmem_dir_free(page); 458 freed++; 459 if (freed >= LATENCY_LIMIT) { 460 cond_resched(); 461 freed = 0; 462 } 463 } while (next); 464} 465 466static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) 467{ 468 struct shmem_inode_info *info = SHMEM_I(inode); 469 unsigned long idx; 470 unsigned long size; 471 unsigned long limit; 472 unsigned long stage; 473 unsigned long diroff; 474 struct page **dir; 475 struct page *topdir; 476 struct page *middir; 477 struct page *subdir; 478 swp_entry_t *ptr; 479 LIST_HEAD(pages_to_free); 480 long nr_pages_to_free = 0; 481 long nr_swaps_freed = 0; 482 int offset; 483 int freed; 484 int punch_hole = 0; 485 486 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 487 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 488 if (idx >= info->next_index) 489 return; 490 491 spin_lock(&info->lock); 492 info->flags |= SHMEM_TRUNCATE; 493 if (likely(end == (loff_t) -1)) { 494 limit = info->next_index; 495 info->next_index = idx; 496 } else { 497 limit = (end + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 498 if (limit > info->next_index) 499 limit = info->next_index; 500 punch_hole = 1; 501 } 502 503 topdir = info->i_indirect; 504 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { 505 info->i_indirect = NULL; 506 nr_pages_to_free++; 507 list_add(&topdir->lru, &pages_to_free); 508 } 509 spin_unlock(&info->lock); 510 511 if (info->swapped && idx < SHMEM_NR_DIRECT) { 512 ptr = info->i_direct; 513 size = limit; 514 if (size > SHMEM_NR_DIRECT) 515 size = SHMEM_NR_DIRECT; 516 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size); 517 } 518 519 /* 520 * If there are no indirect blocks or we are punching a hole 521 * below indirect blocks, nothing to be done. 522 */ 523 if (!topdir || (punch_hole && (limit <= SHMEM_NR_DIRECT))) 524 goto done2; 525 526 BUG_ON(limit <= SHMEM_NR_DIRECT); 527 limit -= SHMEM_NR_DIRECT; 528 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 529 offset = idx % ENTRIES_PER_PAGE; 530 idx -= offset; 531 532 dir = shmem_dir_map(topdir); 533 stage = ENTRIES_PER_PAGEPAGE/2; 534 if (idx < ENTRIES_PER_PAGEPAGE/2) { 535 middir = topdir; 536 diroff = idx/ENTRIES_PER_PAGE; 537 } else { 538 dir += ENTRIES_PER_PAGE/2; 539 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 540 while (stage <= idx) 541 stage += ENTRIES_PER_PAGEPAGE; 542 middir = *dir; 543 if (*dir) { 544 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 545 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 546 if (!diroff && !offset) { 547 *dir = NULL; 548 nr_pages_to_free++; 549 list_add(&middir->lru, &pages_to_free); 550 } 551 shmem_dir_unmap(dir); 552 dir = shmem_dir_map(middir); 553 } else { 554 diroff = 0; 555 offset = 0; 556 idx = stage; 557 } 558 } 559 560 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 561 if (unlikely(idx == stage)) { 562 shmem_dir_unmap(dir); 563 dir = shmem_dir_map(topdir) + 564 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 565 while (!*dir) { 566 dir++; 567 idx += ENTRIES_PER_PAGEPAGE; 568 if (idx >= limit) 569 goto done1; 570 } 571 stage = idx + ENTRIES_PER_PAGEPAGE; 572 middir = *dir; 573 *dir = NULL; 574 nr_pages_to_free++; 575 list_add(&middir->lru, &pages_to_free); 576 shmem_dir_unmap(dir); 577 cond_resched(); 578 dir = shmem_dir_map(middir); 579 diroff = 0; 580 } 581 subdir = dir[diroff]; 582 if (subdir && page_private(subdir)) { 583 size = limit - idx; 584 if (size > ENTRIES_PER_PAGE) 585 size = ENTRIES_PER_PAGE; 586 freed = shmem_map_and_free_swp(subdir, 587 offset, size, &dir); 588 if (!dir) 589 dir = shmem_dir_map(middir); 590 nr_swaps_freed += freed; 591 if (offset) 592 spin_lock(&info->lock); 593 set_page_private(subdir, page_private(subdir) - freed); 594 if (offset) 595 spin_unlock(&info->lock); 596 if (!punch_hole) 597 BUG_ON(page_private(subdir) > offset); 598 } 599 if (offset) 600 offset = 0; 601 else if (subdir && !page_private(subdir)) { 602 dir[diroff] = NULL; 603 nr_pages_to_free++; 604 list_add(&subdir->lru, &pages_to_free); 605 } 606 } 607done1: 608 shmem_dir_unmap(dir); 609done2: 610 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 611 /* 612 * Call truncate_inode_pages again: racing shmem_unuse_inode 613 * may have swizzled a page in from swap since vmtruncate or 614 * generic_delete_inode did it, before we lowered next_index. 615 * Also, though shmem_getpage checks i_size before adding to 616 * cache, no recheck after: so fix the narrow window there too. 617 */ 618 truncate_inode_pages_range(inode->i_mapping, start, end); 619 } 620 621 spin_lock(&info->lock); 622 info->flags &= ~SHMEM_TRUNCATE; 623 info->swapped -= nr_swaps_freed; 624 if (nr_pages_to_free) 625 shmem_free_blocks(inode, nr_pages_to_free); 626 shmem_recalc_inode(inode); 627 spin_unlock(&info->lock); 628 629 /* 630 * Empty swap vector directory pages to be freed? 631 */ 632 if (!list_empty(&pages_to_free)) { 633 pages_to_free.prev->next = NULL; 634 shmem_free_pages(pages_to_free.next); 635 } 636} 637 638static void shmem_truncate(struct inode *inode) 639{ 640 shmem_truncate_range(inode, inode->i_size, (loff_t)-1); 641} 642 643static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 644{ 645 struct inode *inode = dentry->d_inode; 646 struct page *page = NULL; 647 int error; 648 649 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { 650 if (attr->ia_size < inode->i_size) { 651 /* 652 * If truncating down to a partial page, then 653 * if that page is already allocated, hold it 654 * in memory until the truncation is over, so 655 * truncate_partial_page cannnot miss it were 656 * it assigned to swap. 657 */ 658 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { 659 (void) shmem_getpage(inode, 660 attr->ia_size>>PAGE_CACHE_SHIFT, 661 &page, SGP_READ, NULL); 662 } 663 /* 664 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 665 * detect if any pages might have been added to cache 666 * after truncate_inode_pages. But we needn't bother 667 * if it's being fully truncated to zero-length: the 668 * nrpages check is efficient enough in that case. 669 */ 670 if (attr->ia_size) { 671 struct shmem_inode_info *info = SHMEM_I(inode); 672 spin_lock(&info->lock); 673 info->flags &= ~SHMEM_PAGEIN; 674 spin_unlock(&info->lock); 675 } 676 } 677 } 678 679 error = inode_change_ok(inode, attr); 680 if (!error) 681 error = inode_setattr(inode, attr); 682#ifdef CONFIG_TMPFS_POSIX_ACL 683 if (!error && (attr->ia_valid & ATTR_MODE)) 684 error = generic_acl_chmod(inode, &shmem_acl_ops); 685#endif 686 if (page) 687 page_cache_release(page); 688 return error; 689} 690 691static void shmem_delete_inode(struct inode *inode) 692{ 693 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 694 struct shmem_inode_info *info = SHMEM_I(inode); 695 696 if (inode->i_op->truncate == shmem_truncate) { 697 truncate_inode_pages(inode->i_mapping, 0); 698 shmem_unacct_size(info->flags, inode->i_size); 699 inode->i_size = 0; 700 shmem_truncate(inode); 701 if (!list_empty(&info->swaplist)) { 702 spin_lock(&shmem_swaplist_lock); 703 list_del_init(&info->swaplist); 704 spin_unlock(&shmem_swaplist_lock); 705 } 706 } 707 BUG_ON(inode->i_blocks); 708 if (sbinfo->max_inodes) { 709 spin_lock(&sbinfo->stat_lock); 710 sbinfo->free_inodes++; 711 spin_unlock(&sbinfo->stat_lock); 712 } 713 clear_inode(inode); 714} 715 716static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 717{ 718 swp_entry_t *ptr; 719 720 for (ptr = dir; ptr < edir; ptr++) { 721 if (ptr->val == entry.val) 722 return ptr - dir; 723 } 724 return -1; 725} 726 727static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 728{ 729 struct inode *inode; 730 unsigned long idx; 731 unsigned long size; 732 unsigned long limit; 733 unsigned long stage; 734 struct page **dir; 735 struct page *subdir; 736 swp_entry_t *ptr; 737 int offset; 738 739 idx = 0; 740 ptr = info->i_direct; 741 spin_lock(&info->lock); 742 limit = info->next_index; 743 size = limit; 744 if (size > SHMEM_NR_DIRECT) 745 size = SHMEM_NR_DIRECT; 746 offset = shmem_find_swp(entry, ptr, ptr+size); 747 if (offset >= 0) { 748 shmem_swp_balance_unmap(); 749 goto found; 750 } 751 if (!info->i_indirect) 752 goto lost2; 753 754 dir = shmem_dir_map(info->i_indirect); 755 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 756 757 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 758 if (unlikely(idx == stage)) { 759 shmem_dir_unmap(dir-1); 760 dir = shmem_dir_map(info->i_indirect) + 761 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 762 while (!*dir) { 763 dir++; 764 idx += ENTRIES_PER_PAGEPAGE; 765 if (idx >= limit) 766 goto lost1; 767 } 768 stage = idx + ENTRIES_PER_PAGEPAGE; 769 subdir = *dir; 770 shmem_dir_unmap(dir); 771 dir = shmem_dir_map(subdir); 772 } 773 subdir = *dir; 774 if (subdir && page_private(subdir)) { 775 ptr = shmem_swp_map(subdir); 776 size = limit - idx; 777 if (size > ENTRIES_PER_PAGE) 778 size = ENTRIES_PER_PAGE; 779 offset = shmem_find_swp(entry, ptr, ptr+size); 780 if (offset >= 0) { 781 shmem_dir_unmap(dir); 782 goto found; 783 } 784 shmem_swp_unmap(ptr); 785 } 786 } 787lost1: 788 shmem_dir_unmap(dir-1); 789lost2: 790 spin_unlock(&info->lock); 791 return 0; 792found: 793 idx += offset; 794 inode = &info->vfs_inode; 795 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) { 796 info->flags |= SHMEM_PAGEIN; 797 shmem_swp_set(info, ptr + offset, 0); 798 } 799 shmem_swp_unmap(ptr); 800 spin_unlock(&info->lock); 801 /* 802 * Decrement swap count even when the entry is left behind: 803 * try_to_unuse will skip over mms, then reincrement count. 804 */ 805 swap_free(entry); 806 return 1; 807} 808 809/* 810 * shmem_unuse() search for an eventually swapped out shmem page. 811 */ 812int shmem_unuse(swp_entry_t entry, struct page *page) 813{ 814 struct list_head *p, *next; 815 struct shmem_inode_info *info; 816 int found = 0; 817 818 spin_lock(&shmem_swaplist_lock); 819 list_for_each_safe(p, next, &shmem_swaplist) { 820 info = list_entry(p, struct shmem_inode_info, swaplist); 821 if (!info->swapped) 822 list_del_init(&info->swaplist); 823 else if (shmem_unuse_inode(info, entry, page)) { 824 /* move head to start search for next from here */ 825 list_move_tail(&shmem_swaplist, &info->swaplist); 826 found = 1; 827 break; 828 } 829 } 830 spin_unlock(&shmem_swaplist_lock); 831 return found; 832} 833 834/* 835 * Move the page from the page cache to the swap cache. 836 */ 837static int shmem_writepage(struct page *page, struct writeback_control *wbc) 838{ 839 struct shmem_inode_info *info; 840 swp_entry_t *entry, swap; 841 struct address_space *mapping; 842 unsigned long index; 843 struct inode *inode; 844 845 BUG_ON(!PageLocked(page)); 846 BUG_ON(page_mapped(page)); 847 848 mapping = page->mapping; 849 index = page->index; 850 inode = mapping->host; 851 info = SHMEM_I(inode); 852 if (info->flags & VM_LOCKED) 853 goto redirty; 854 swap = get_swap_page(); 855 if (!swap.val) 856 goto redirty; 857 858 spin_lock(&info->lock); 859 shmem_recalc_inode(inode); 860 if (index >= info->next_index) { 861 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 862 goto unlock; 863 } 864 entry = shmem_swp_entry(info, index, NULL); 865 BUG_ON(!entry); 866 BUG_ON(entry->val); 867 868 if (move_to_swap_cache(page, swap) == 0) { 869 shmem_swp_set(info, entry, swap.val); 870 shmem_swp_unmap(entry); 871 spin_unlock(&info->lock); 872 if (list_empty(&info->swaplist)) { 873 spin_lock(&shmem_swaplist_lock); 874 /* move instead of add in case we're racing */ 875 list_move_tail(&info->swaplist, &shmem_swaplist); 876 spin_unlock(&shmem_swaplist_lock); 877 } 878 unlock_page(page); 879 return 0; 880 } 881 882 shmem_swp_unmap(entry); 883unlock: 884 spin_unlock(&info->lock); 885 swap_free(swap); 886redirty: 887 set_page_dirty(page); 888 return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */ 889} 890 891#ifdef CONFIG_NUMA 892static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 893{ 894 char *nodelist = strchr(value, ':'); 895 int err = 1; 896 897 if (nodelist) { 898 /* NUL-terminate policy string */ 899 *nodelist++ = '\0'; 900 if (nodelist_parse(nodelist, *policy_nodes)) 901 goto out; 902 } 903 if (!strcmp(value, "default")) { 904 *policy = MPOL_DEFAULT; 905 /* Don't allow a nodelist */ 906 if (!nodelist) 907 err = 0; 908 } else if (!strcmp(value, "prefer")) { 909 *policy = MPOL_PREFERRED; 910 /* Insist on a nodelist of one node only */ 911 if (nodelist) { 912 char *rest = nodelist; 913 while (isdigit(*rest)) 914 rest++; 915 if (!*rest) 916 err = 0; 917 } 918 } else if (!strcmp(value, "bind")) { 919 *policy = MPOL_BIND; 920 /* Insist on a nodelist */ 921 if (nodelist) 922 err = 0; 923 } else if (!strcmp(value, "interleave")) { 924 *policy = MPOL_INTERLEAVE; 925 /* Default to nodes online if no nodelist */ 926 if (!nodelist) 927 *policy_nodes = node_online_map; 928 err = 0; 929 } 930out: 931 /* Restore string for error message */ 932 if (nodelist) 933 *--nodelist = ':'; 934 return err; 935} 936 937static struct page *shmem_swapin_async(struct shared_policy *p, 938 swp_entry_t entry, unsigned long idx) 939{ 940 struct page *page; 941 struct vm_area_struct pvma; 942 943 /* Create a pseudo vma that just contains the policy */ 944 memset(&pvma, 0, sizeof(struct vm_area_struct)); 945 pvma.vm_end = PAGE_SIZE; 946 pvma.vm_pgoff = idx; 947 pvma.vm_policy = mpol_shared_policy_lookup(p, idx); 948 page = read_swap_cache_async(entry, &pvma, 0); 949 mpol_free(pvma.vm_policy); 950 return page; 951} 952 953struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry, 954 unsigned long idx) 955{ 956 struct shared_policy *p = &info->policy; 957 int i, num; 958 struct page *page; 959 unsigned long offset; 960 961 num = valid_swaphandles(entry, &offset); 962 for (i = 0; i < num; offset++, i++) { 963 page = shmem_swapin_async(p, 964 swp_entry(swp_type(entry), offset), idx); 965 if (!page) 966 break; 967 page_cache_release(page); 968 } 969 lru_add_drain(); /* Push any new pages onto the LRU now */ 970 return shmem_swapin_async(p, entry, idx); 971} 972 973static struct page * 974shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, 975 unsigned long idx) 976{ 977 struct vm_area_struct pvma; 978 struct page *page; 979 980 memset(&pvma, 0, sizeof(struct vm_area_struct)); 981 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 982 pvma.vm_pgoff = idx; 983 pvma.vm_end = PAGE_SIZE; 984 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0); 985 mpol_free(pvma.vm_policy); 986 return page; 987} 988#else 989static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 990{ 991 return 1; 992} 993 994static inline struct page * 995shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx) 996{ 997 swapin_readahead(entry, 0, NULL); 998 return read_swap_cache_async(entry, NULL, 0); 999} 1000 1001static inline struct page * 1002shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx) 1003{ 1004 return alloc_page(gfp | __GFP_ZERO); 1005} 1006#endif 1007 1008/* 1009 * shmem_getpage - either get the page from swap or allocate a new one 1010 * 1011 * If we allocate a new one we do not mark it dirty. That's up to the 1012 * vm. If we swap it in we mark it dirty since we also free the swap 1013 * entry since a page cannot live in both the swap and page cache 1014 */ 1015static int shmem_getpage(struct inode *inode, unsigned long idx, 1016 struct page **pagep, enum sgp_type sgp, int *type) 1017{ 1018 struct address_space *mapping = inode->i_mapping; 1019 struct shmem_inode_info *info = SHMEM_I(inode); 1020 struct shmem_sb_info *sbinfo; 1021 struct page *filepage = *pagep; 1022 struct page *swappage; 1023 swp_entry_t *entry; 1024 swp_entry_t swap; 1025 int error; 1026 1027 if (idx >= SHMEM_MAX_INDEX) 1028 return -EFBIG; 1029 /* 1030 * Normally, filepage is NULL on entry, and either found 1031 * uptodate immediately, or allocated and zeroed, or read 1032 * in under swappage, which is then assigned to filepage. 1033 * But shmem_prepare_write passes in a locked filepage, 1034 * which may be found not uptodate by other callers too, 1035 * and may need to be copied from the swappage read in. 1036 */ 1037repeat: 1038 if (!filepage) 1039 filepage = find_lock_page(mapping, idx); 1040 if (filepage && PageUptodate(filepage)) 1041 goto done; 1042 error = 0; 1043 if (sgp == SGP_QUICK) 1044 goto failed; 1045 1046 spin_lock(&info->lock); 1047 shmem_recalc_inode(inode); 1048 entry = shmem_swp_alloc(info, idx, sgp); 1049 if (IS_ERR(entry)) { 1050 spin_unlock(&info->lock); 1051 error = PTR_ERR(entry); 1052 goto failed; 1053 } 1054 swap = *entry; 1055 1056 if (swap.val) { 1057 /* Look it up and read it in.. */ 1058 swappage = lookup_swap_cache(swap); 1059 if (!swappage) { 1060 shmem_swp_unmap(entry); 1061 /* here we actually do the io */ 1062 if (type && *type == VM_FAULT_MINOR) { 1063 __count_vm_event(PGMAJFAULT); 1064 *type = VM_FAULT_MAJOR; 1065 } 1066 spin_unlock(&info->lock); 1067 swappage = shmem_swapin(info, swap, idx); 1068 if (!swappage) { 1069 spin_lock(&info->lock); 1070 entry = shmem_swp_alloc(info, idx, sgp); 1071 if (IS_ERR(entry)) 1072 error = PTR_ERR(entry); 1073 else { 1074 if (entry->val == swap.val) 1075 error = -ENOMEM; 1076 shmem_swp_unmap(entry); 1077 } 1078 spin_unlock(&info->lock); 1079 if (error) 1080 goto failed; 1081 goto repeat; 1082 } 1083 wait_on_page_locked(swappage); 1084 page_cache_release(swappage); 1085 goto repeat; 1086 } 1087 1088 /* We have to do this with page locked to prevent races */ 1089 if (TestSetPageLocked(swappage)) { 1090 shmem_swp_unmap(entry); 1091 spin_unlock(&info->lock); 1092 wait_on_page_locked(swappage); 1093 page_cache_release(swappage); 1094 goto repeat; 1095 } 1096 if (PageWriteback(swappage)) { 1097 shmem_swp_unmap(entry); 1098 spin_unlock(&info->lock); 1099 wait_on_page_writeback(swappage); 1100 unlock_page(swappage); 1101 page_cache_release(swappage); 1102 goto repeat; 1103 } 1104 if (!PageUptodate(swappage)) { 1105 shmem_swp_unmap(entry); 1106 spin_unlock(&info->lock); 1107 unlock_page(swappage); 1108 page_cache_release(swappage); 1109 error = -EIO; 1110 goto failed; 1111 } 1112 1113 if (filepage) { 1114 shmem_swp_set(info, entry, 0); 1115 shmem_swp_unmap(entry); 1116 delete_from_swap_cache(swappage); 1117 spin_unlock(&info->lock); 1118 copy_highpage(filepage, swappage); 1119 unlock_page(swappage); 1120 page_cache_release(swappage); 1121 flush_dcache_page(filepage); 1122 SetPageUptodate(filepage); 1123 set_page_dirty(filepage); 1124 swap_free(swap); 1125 } else if (!(error = move_from_swap_cache( 1126 swappage, idx, mapping))) { 1127 info->flags |= SHMEM_PAGEIN; 1128 shmem_swp_set(info, entry, 0); 1129 shmem_swp_unmap(entry); 1130 spin_unlock(&info->lock); 1131 filepage = swappage; 1132 swap_free(swap); 1133 } else { 1134 shmem_swp_unmap(entry); 1135 spin_unlock(&info->lock); 1136 unlock_page(swappage); 1137 page_cache_release(swappage); 1138 if (error == -ENOMEM) { 1139 /* let kswapd refresh zone for GFP_ATOMICs */ 1140 congestion_wait(WRITE, HZ/50); 1141 } 1142 goto repeat; 1143 } 1144 } else if (sgp == SGP_READ && !filepage) { 1145 shmem_swp_unmap(entry); 1146 filepage = find_get_page(mapping, idx); 1147 if (filepage && 1148 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1149 spin_unlock(&info->lock); 1150 wait_on_page_locked(filepage); 1151 page_cache_release(filepage); 1152 filepage = NULL; 1153 goto repeat; 1154 } 1155 spin_unlock(&info->lock); 1156 } else { 1157 shmem_swp_unmap(entry); 1158 sbinfo = SHMEM_SB(inode->i_sb); 1159 if (sbinfo->max_blocks) { 1160 spin_lock(&sbinfo->stat_lock); 1161 if (sbinfo->free_blocks == 0 || 1162 shmem_acct_block(info->flags)) { 1163 spin_unlock(&sbinfo->stat_lock); 1164 spin_unlock(&info->lock); 1165 error = -ENOSPC; 1166 goto failed; 1167 } 1168 sbinfo->free_blocks--; 1169 inode->i_blocks += BLOCKS_PER_PAGE; 1170 spin_unlock(&sbinfo->stat_lock); 1171 } else if (shmem_acct_block(info->flags)) { 1172 spin_unlock(&info->lock); 1173 error = -ENOSPC; 1174 goto failed; 1175 } 1176 1177 if (!filepage) { 1178 spin_unlock(&info->lock); 1179 filepage = shmem_alloc_page(mapping_gfp_mask(mapping), 1180 info, 1181 idx); 1182 if (!filepage) { 1183 shmem_unacct_blocks(info->flags, 1); 1184 shmem_free_blocks(inode, 1); 1185 error = -ENOMEM; 1186 goto failed; 1187 } 1188 1189 spin_lock(&info->lock); 1190 entry = shmem_swp_alloc(info, idx, sgp); 1191 if (IS_ERR(entry)) 1192 error = PTR_ERR(entry); 1193 else { 1194 swap = *entry; 1195 shmem_swp_unmap(entry); 1196 } 1197 if (error || swap.val || 0 != add_to_page_cache_lru( 1198 filepage, mapping, idx, GFP_ATOMIC)) { 1199 spin_unlock(&info->lock); 1200 page_cache_release(filepage); 1201 shmem_unacct_blocks(info->flags, 1); 1202 shmem_free_blocks(inode, 1); 1203 filepage = NULL; 1204 if (error) 1205 goto failed; 1206 goto repeat; 1207 } 1208 info->flags |= SHMEM_PAGEIN; 1209 } 1210 1211 info->alloced++; 1212 spin_unlock(&info->lock); 1213 flush_dcache_page(filepage); 1214 SetPageUptodate(filepage); 1215 } 1216done: 1217 if (*pagep != filepage) { 1218 unlock_page(filepage); 1219 *pagep = filepage; 1220 } 1221 return 0; 1222 1223failed: 1224 if (*pagep != filepage) { 1225 unlock_page(filepage); 1226 page_cache_release(filepage); 1227 } 1228 return error; 1229} 1230 1231struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type) 1232{ 1233 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1234 struct page *page = NULL; 1235 unsigned long idx; 1236 int error; 1237 1238 idx = (address - vma->vm_start) >> PAGE_SHIFT; 1239 idx += vma->vm_pgoff; 1240 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT; 1241 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1242 return NOPAGE_SIGBUS; 1243 1244 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type); 1245 if (error) 1246 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS; 1247 1248 mark_page_accessed(page); 1249 return page; 1250} 1251 1252static int shmem_populate(struct vm_area_struct *vma, 1253 unsigned long addr, unsigned long len, 1254 pgprot_t prot, unsigned long pgoff, int nonblock) 1255{ 1256 struct inode *inode = vma->vm_file->f_path.dentry->d_inode; 1257 struct mm_struct *mm = vma->vm_mm; 1258 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE; 1259 unsigned long size; 1260 1261 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; 1262 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size) 1263 return -EINVAL; 1264 1265 while ((long) len > 0) { 1266 struct page *page = NULL; 1267 int err; 1268 /* 1269 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE 1270 */ 1271 err = shmem_getpage(inode, pgoff, &page, sgp, NULL); 1272 if (err) 1273 return err; 1274 /* Page may still be null, but only if nonblock was set. */ 1275 if (page) { 1276 mark_page_accessed(page); 1277 err = install_page(mm, vma, addr, page, prot); 1278 if (err) { 1279 page_cache_release(page); 1280 return err; 1281 } 1282 } else if (vma->vm_flags & VM_NONLINEAR) { 1283 /* No page was found just because we can't read it in 1284 * now (being here implies nonblock != 0), but the page 1285 * may exist, so set the PTE to fault it in later. */ 1286 err = install_file_pte(mm, vma, addr, pgoff, prot); 1287 if (err) 1288 return err; 1289 } 1290 1291 len -= PAGE_SIZE; 1292 addr += PAGE_SIZE; 1293 pgoff++; 1294 } 1295 return 0; 1296} 1297 1298#ifdef CONFIG_NUMA 1299int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1300{ 1301 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1302 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1303} 1304 1305struct mempolicy * 1306shmem_get_policy(struct vm_area_struct *vma, unsigned long addr) 1307{ 1308 struct inode *i = vma->vm_file->f_path.dentry->d_inode; 1309 unsigned long idx; 1310 1311 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1312 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1313} 1314#endif 1315 1316int shmem_lock(struct file *file, int lock, struct user_struct *user) 1317{ 1318 struct inode *inode = file->f_path.dentry->d_inode; 1319 struct shmem_inode_info *info = SHMEM_I(inode); 1320 int retval = -ENOMEM; 1321 1322 spin_lock(&info->lock); 1323 if (lock && !(info->flags & VM_LOCKED)) { 1324 if (!user_shm_lock(inode->i_size, user)) 1325 goto out_nomem; 1326 info->flags |= VM_LOCKED; 1327 } 1328 if (!lock && (info->flags & VM_LOCKED) && user) { 1329 user_shm_unlock(inode->i_size, user); 1330 info->flags &= ~VM_LOCKED; 1331 } 1332 retval = 0; 1333out_nomem: 1334 spin_unlock(&info->lock); 1335 return retval; 1336} 1337 1338int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1339{ 1340 file_accessed(file); 1341 vma->vm_ops = &shmem_vm_ops; 1342 return 0; 1343} 1344 1345static struct inode * 1346shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1347{ 1348 struct inode *inode; 1349 struct shmem_inode_info *info; 1350 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1351 1352 if (sbinfo->max_inodes) { 1353 spin_lock(&sbinfo->stat_lock); 1354 if (!sbinfo->free_inodes) { 1355 spin_unlock(&sbinfo->stat_lock); 1356 return NULL; 1357 } 1358 sbinfo->free_inodes--; 1359 spin_unlock(&sbinfo->stat_lock); 1360 } 1361 1362 inode = new_inode(sb); 1363 if (inode) { 1364 inode->i_mode = mode; 1365 inode->i_uid = current->fsuid; 1366 inode->i_gid = current->fsgid; 1367 inode->i_blocks = 0; 1368 inode->i_mapping->a_ops = &shmem_aops; 1369 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1370 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1371 inode->i_generation = get_seconds(); 1372 info = SHMEM_I(inode); 1373 memset(info, 0, (char *)inode - (char *)info); 1374 spin_lock_init(&info->lock); 1375 INIT_LIST_HEAD(&info->swaplist); 1376 1377 switch (mode & S_IFMT) { 1378 default: 1379 inode->i_op = &shmem_special_inode_operations; 1380 init_special_inode(inode, mode, dev); 1381 break; 1382 case S_IFREG: 1383 inode->i_op = &shmem_inode_operations; 1384 inode->i_fop = &shmem_file_operations; 1385 mpol_shared_policy_init(&info->policy, sbinfo->policy, 1386 &sbinfo->policy_nodes); 1387 break; 1388 case S_IFDIR: 1389 inc_nlink(inode); 1390 /* Some things misbehave if size == 0 on a directory */ 1391 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1392 inode->i_op = &shmem_dir_inode_operations; 1393 inode->i_fop = &simple_dir_operations; 1394 break; 1395 case S_IFLNK: 1396 /* 1397 * Must not load anything in the rbtree, 1398 * mpol_free_shared_policy will not be called. 1399 */ 1400 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, 1401 NULL); 1402 break; 1403 } 1404 } else if (sbinfo->max_inodes) { 1405 spin_lock(&sbinfo->stat_lock); 1406 sbinfo->free_inodes++; 1407 spin_unlock(&sbinfo->stat_lock); 1408 } 1409 return inode; 1410} 1411 1412#ifdef CONFIG_TMPFS 1413static struct inode_operations shmem_symlink_inode_operations; 1414static struct inode_operations shmem_symlink_inline_operations; 1415 1416/* 1417 * Normally tmpfs makes no use of shmem_prepare_write, but it 1418 * lets a tmpfs file be used read-write below the loop driver. 1419 */ 1420static int 1421shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to) 1422{ 1423 struct inode *inode = page->mapping->host; 1424 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL); 1425} 1426 1427static ssize_t 1428shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 1429{ 1430 struct inode *inode = file->f_path.dentry->d_inode; 1431 loff_t pos; 1432 unsigned long written; 1433 ssize_t err; 1434 1435 if ((ssize_t) count < 0) 1436 return -EINVAL; 1437 1438 if (!access_ok(VERIFY_READ, buf, count)) 1439 return -EFAULT; 1440 1441 mutex_lock(&inode->i_mutex); 1442 1443 pos = *ppos; 1444 written = 0; 1445 1446 err = generic_write_checks(file, &pos, &count, 0); 1447 if (err || !count) 1448 goto out; 1449 1450 err = remove_suid(file->f_path.dentry); 1451 if (err) 1452 goto out; 1453 1454 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 1455 1456 do { 1457 struct page *page = NULL; 1458 unsigned long bytes, index, offset; 1459 char *kaddr; 1460 int left; 1461 1462 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1463 index = pos >> PAGE_CACHE_SHIFT; 1464 bytes = PAGE_CACHE_SIZE - offset; 1465 if (bytes > count) 1466 bytes = count; 1467 1468 /* 1469 * We don't hold page lock across copy from user - 1470 * what would it guard against? - so no deadlock here. 1471 * But it still may be a good idea to prefault below. 1472 */ 1473 1474 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL); 1475 if (err) 1476 break; 1477 1478 left = bytes; 1479 if (PageHighMem(page)) { 1480 volatile unsigned char dummy; 1481 __get_user(dummy, buf); 1482 __get_user(dummy, buf + bytes - 1); 1483 1484 kaddr = kmap_atomic(page, KM_USER0); 1485 left = __copy_from_user_inatomic(kaddr + offset, 1486 buf, bytes); 1487 kunmap_atomic(kaddr, KM_USER0); 1488 } 1489 if (left) { 1490 kaddr = kmap(page); 1491 left = __copy_from_user(kaddr + offset, buf, bytes); 1492 kunmap(page); 1493 } 1494 1495 written += bytes; 1496 count -= bytes; 1497 pos += bytes; 1498 buf += bytes; 1499 if (pos > inode->i_size) 1500 i_size_write(inode, pos); 1501 1502 flush_dcache_page(page); 1503 set_page_dirty(page); 1504 mark_page_accessed(page); 1505 page_cache_release(page); 1506 1507 if (left) { 1508 pos -= left; 1509 written -= left; 1510 err = -EFAULT; 1511 break; 1512 } 1513 1514 /* 1515 * Our dirty pages are not counted in nr_dirty, 1516 * and we do not attempt to balance dirty pages. 1517 */ 1518 1519 cond_resched(); 1520 } while (count); 1521 1522 *ppos = pos; 1523 if (written) 1524 err = written; 1525out: 1526 mutex_unlock(&inode->i_mutex); 1527 return err; 1528} 1529 1530static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1531{ 1532 struct inode *inode = filp->f_path.dentry->d_inode; 1533 struct address_space *mapping = inode->i_mapping; 1534 unsigned long index, offset; 1535 1536 index = *ppos >> PAGE_CACHE_SHIFT; 1537 offset = *ppos & ~PAGE_CACHE_MASK; 1538 1539 for (;;) { 1540 struct page *page = NULL; 1541 unsigned long end_index, nr, ret; 1542 loff_t i_size = i_size_read(inode); 1543 1544 end_index = i_size >> PAGE_CACHE_SHIFT; 1545 if (index > end_index) 1546 break; 1547 if (index == end_index) { 1548 nr = i_size & ~PAGE_CACHE_MASK; 1549 if (nr <= offset) 1550 break; 1551 } 1552 1553 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL); 1554 if (desc->error) { 1555 if (desc->error == -EINVAL) 1556 desc->error = 0; 1557 break; 1558 } 1559 1560 /* 1561 * We must evaluate after, since reads (unlike writes) 1562 * are called without i_mutex protection against truncate 1563 */ 1564 nr = PAGE_CACHE_SIZE; 1565 i_size = i_size_read(inode); 1566 end_index = i_size >> PAGE_CACHE_SHIFT; 1567 if (index == end_index) { 1568 nr = i_size & ~PAGE_CACHE_MASK; 1569 if (nr <= offset) { 1570 if (page) 1571 page_cache_release(page); 1572 break; 1573 } 1574 } 1575 nr -= offset; 1576 1577 if (page) { 1578 /* 1579 * If users can be writing to this page using arbitrary 1580 * virtual addresses, take care about potential aliasing 1581 * before reading the page on the kernel side. 1582 */ 1583 if (mapping_writably_mapped(mapping)) 1584 flush_dcache_page(page); 1585 /* 1586 * Mark the page accessed if we read the beginning. 1587 */ 1588 if (!offset) 1589 mark_page_accessed(page); 1590 } else { 1591 page = ZERO_PAGE(0); 1592 page_cache_get(page); 1593 } 1594 1595 /* 1596 * Ok, we have the page, and it's up-to-date, so 1597 * now we can copy it to user space... 1598 * 1599 * The actor routine returns how many bytes were actually used.. 1600 * NOTE! This may not be the same as how much of a user buffer 1601 * we filled up (we may be padding etc), so we can only update 1602 * "pos" here (the actor routine has to update the user buffer 1603 * pointers and the remaining count). 1604 */ 1605 ret = actor(desc, page, offset, nr); 1606 offset += ret; 1607 index += offset >> PAGE_CACHE_SHIFT; 1608 offset &= ~PAGE_CACHE_MASK; 1609 1610 page_cache_release(page); 1611 if (ret != nr || !desc->count) 1612 break; 1613 1614 cond_resched(); 1615 } 1616 1617 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1618 file_accessed(filp); 1619} 1620 1621static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1622{ 1623 read_descriptor_t desc; 1624 1625 if ((ssize_t) count < 0) 1626 return -EINVAL; 1627 if (!access_ok(VERIFY_WRITE, buf, count)) 1628 return -EFAULT; 1629 if (!count) 1630 return 0; 1631 1632 desc.written = 0; 1633 desc.count = count; 1634 desc.arg.buf = buf; 1635 desc.error = 0; 1636 1637 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1638 if (desc.written) 1639 return desc.written; 1640 return desc.error; 1641} 1642 1643static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos, 1644 size_t count, read_actor_t actor, void *target) 1645{ 1646 read_descriptor_t desc; 1647 1648 if (!count) 1649 return 0; 1650 1651 desc.written = 0; 1652 desc.count = count; 1653 desc.arg.data = target; 1654 desc.error = 0; 1655 1656 do_shmem_file_read(in_file, ppos, &desc, actor); 1657 if (desc.written) 1658 return desc.written; 1659 return desc.error; 1660} 1661 1662static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1663{ 1664 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1665 1666 buf->f_type = TMPFS_MAGIC; 1667 buf->f_bsize = PAGE_CACHE_SIZE; 1668 buf->f_namelen = NAME_MAX; 1669 spin_lock(&sbinfo->stat_lock); 1670 if (sbinfo->max_blocks) { 1671 buf->f_blocks = sbinfo->max_blocks; 1672 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1673 } 1674 if (sbinfo->max_inodes) { 1675 buf->f_files = sbinfo->max_inodes; 1676 buf->f_ffree = sbinfo->free_inodes; 1677 } 1678 /* else leave those fields 0 like simple_statfs */ 1679 spin_unlock(&sbinfo->stat_lock); 1680 return 0; 1681} 1682 1683/* 1684 * File creation. Allocate an inode, and we're done.. 1685 */ 1686static int 1687shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1688{ 1689 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1690 int error = -ENOSPC; 1691 1692 if (inode) { 1693 error = security_inode_init_security(inode, dir, NULL, NULL, 1694 NULL); 1695 if (error) { 1696 if (error != -EOPNOTSUPP) { 1697 iput(inode); 1698 return error; 1699 } 1700 } 1701 error = shmem_acl_init(inode, dir); 1702 if (error) { 1703 iput(inode); 1704 return error; 1705 } 1706 if (dir->i_mode & S_ISGID) { 1707 inode->i_gid = dir->i_gid; 1708 if (S_ISDIR(mode)) 1709 inode->i_mode |= S_ISGID; 1710 } 1711 dir->i_size += BOGO_DIRENT_SIZE; 1712 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1713 d_instantiate(dentry, inode); 1714 dget(dentry); /* Extra count - pin the dentry in core */ 1715 } 1716 return error; 1717} 1718 1719static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1720{ 1721 int error; 1722 1723 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1724 return error; 1725 inc_nlink(dir); 1726 return 0; 1727} 1728 1729static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1730 struct nameidata *nd) 1731{ 1732 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1733} 1734 1735/* 1736 * Link a file.. 1737 */ 1738static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1739{ 1740 struct inode *inode = old_dentry->d_inode; 1741 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1742 1743 /* 1744 * No ordinary (disk based) filesystem counts links as inodes; 1745 * but each new link needs a new dentry, pinning lowmem, and 1746 * tmpfs dentries cannot be pruned until they are unlinked. 1747 */ 1748 if (sbinfo->max_inodes) { 1749 spin_lock(&sbinfo->stat_lock); 1750 if (!sbinfo->free_inodes) { 1751 spin_unlock(&sbinfo->stat_lock); 1752 return -ENOSPC; 1753 } 1754 sbinfo->free_inodes--; 1755 spin_unlock(&sbinfo->stat_lock); 1756 } 1757 1758 dir->i_size += BOGO_DIRENT_SIZE; 1759 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1760 inc_nlink(inode); 1761 atomic_inc(&inode->i_count); /* New dentry reference */ 1762 dget(dentry); /* Extra pinning count for the created dentry */ 1763 d_instantiate(dentry, inode); 1764 return 0; 1765} 1766 1767static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1768{ 1769 struct inode *inode = dentry->d_inode; 1770 1771 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) { 1772 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1773 if (sbinfo->max_inodes) { 1774 spin_lock(&sbinfo->stat_lock); 1775 sbinfo->free_inodes++; 1776 spin_unlock(&sbinfo->stat_lock); 1777 } 1778 } 1779 1780 dir->i_size -= BOGO_DIRENT_SIZE; 1781 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1782 drop_nlink(inode); 1783 dput(dentry); /* Undo the count from "create" - this does all the work */ 1784 return 0; 1785} 1786 1787static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1788{ 1789 if (!simple_empty(dentry)) 1790 return -ENOTEMPTY; 1791 1792 drop_nlink(dentry->d_inode); 1793 drop_nlink(dir); 1794 return shmem_unlink(dir, dentry); 1795} 1796 1797/* 1798 * The VFS layer already does all the dentry stuff for rename, 1799 * we just have to decrement the usage count for the target if 1800 * it exists so that the VFS layer correctly free's it when it 1801 * gets overwritten. 1802 */ 1803static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1804{ 1805 struct inode *inode = old_dentry->d_inode; 1806 int they_are_dirs = S_ISDIR(inode->i_mode); 1807 1808 if (!simple_empty(new_dentry)) 1809 return -ENOTEMPTY; 1810 1811 if (new_dentry->d_inode) { 1812 (void) shmem_unlink(new_dir, new_dentry); 1813 if (they_are_dirs) 1814 drop_nlink(old_dir); 1815 } else if (they_are_dirs) { 1816 drop_nlink(old_dir); 1817 inc_nlink(new_dir); 1818 } 1819 1820 old_dir->i_size -= BOGO_DIRENT_SIZE; 1821 new_dir->i_size += BOGO_DIRENT_SIZE; 1822 old_dir->i_ctime = old_dir->i_mtime = 1823 new_dir->i_ctime = new_dir->i_mtime = 1824 inode->i_ctime = CURRENT_TIME; 1825 return 0; 1826} 1827 1828static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1829{ 1830 int error; 1831 int len; 1832 struct inode *inode; 1833 struct page *page = NULL; 1834 char *kaddr; 1835 struct shmem_inode_info *info; 1836 1837 len = strlen(symname) + 1; 1838 if (len > PAGE_CACHE_SIZE) 1839 return -ENAMETOOLONG; 1840 1841 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1842 if (!inode) 1843 return -ENOSPC; 1844 1845 error = security_inode_init_security(inode, dir, NULL, NULL, 1846 NULL); 1847 if (error) { 1848 if (error != -EOPNOTSUPP) { 1849 iput(inode); 1850 return error; 1851 } 1852 error = 0; 1853 } 1854 1855 info = SHMEM_I(inode); 1856 inode->i_size = len-1; 1857 if (len <= (char *)inode - (char *)info) { 1858 /* do it inline */ 1859 memcpy(info, symname, len); 1860 inode->i_op = &shmem_symlink_inline_operations; 1861 } else { 1862 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1863 if (error) { 1864 iput(inode); 1865 return error; 1866 } 1867 inode->i_op = &shmem_symlink_inode_operations; 1868 kaddr = kmap_atomic(page, KM_USER0); 1869 memcpy(kaddr, symname, len); 1870 kunmap_atomic(kaddr, KM_USER0); 1871 set_page_dirty(page); 1872 page_cache_release(page); 1873 } 1874 if (dir->i_mode & S_ISGID) 1875 inode->i_gid = dir->i_gid; 1876 dir->i_size += BOGO_DIRENT_SIZE; 1877 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1878 d_instantiate(dentry, inode); 1879 dget(dentry); 1880 return 0; 1881} 1882 1883static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1884{ 1885 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1886 return NULL; 1887} 1888 1889static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1890{ 1891 struct page *page = NULL; 1892 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1893 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1894 return page; 1895} 1896 1897static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1898{ 1899 if (!IS_ERR(nd_get_link(nd))) { 1900 struct page *page = cookie; 1901 kunmap(page); 1902 mark_page_accessed(page); 1903 page_cache_release(page); 1904 } 1905} 1906 1907static struct inode_operations shmem_symlink_inline_operations = { 1908 .readlink = generic_readlink, 1909 .follow_link = shmem_follow_link_inline, 1910}; 1911 1912static struct inode_operations shmem_symlink_inode_operations = { 1913 .truncate = shmem_truncate, 1914 .readlink = generic_readlink, 1915 .follow_link = shmem_follow_link, 1916 .put_link = shmem_put_link, 1917}; 1918 1919#ifdef CONFIG_TMPFS_POSIX_ACL 1920/** 1921 * Superblocks without xattr inode operations will get security.* xattr 1922 * support from the VFS "for free". As soon as we have any other xattrs 1923 * like ACLs, we also need to implement the security.* handlers at 1924 * filesystem level, though. 1925 */ 1926 1927static size_t shmem_xattr_security_list(struct inode *inode, char *list, 1928 size_t list_len, const char *name, 1929 size_t name_len) 1930{ 1931 return security_inode_listsecurity(inode, list, list_len); 1932} 1933 1934static int shmem_xattr_security_get(struct inode *inode, const char *name, 1935 void *buffer, size_t size) 1936{ 1937 if (strcmp(name, "") == 0) 1938 return -EINVAL; 1939 return security_inode_getsecurity(inode, name, buffer, size, 1940 -EOPNOTSUPP); 1941} 1942 1943static int shmem_xattr_security_set(struct inode *inode, const char *name, 1944 const void *value, size_t size, int flags) 1945{ 1946 if (strcmp(name, "") == 0) 1947 return -EINVAL; 1948 return security_inode_setsecurity(inode, name, value, size, flags); 1949} 1950 1951static struct xattr_handler shmem_xattr_security_handler = { 1952 .prefix = XATTR_SECURITY_PREFIX, 1953 .list = shmem_xattr_security_list, 1954 .get = shmem_xattr_security_get, 1955 .set = shmem_xattr_security_set, 1956}; 1957 1958static struct xattr_handler *shmem_xattr_handlers[] = { 1959 &shmem_xattr_acl_access_handler, 1960 &shmem_xattr_acl_default_handler, 1961 &shmem_xattr_security_handler, 1962 NULL 1963}; 1964#endif 1965 1966static struct dentry *shmem_get_parent(struct dentry *child) 1967{ 1968 return ERR_PTR(-ESTALE); 1969} 1970 1971static int shmem_match(struct inode *ino, void *vfh) 1972{ 1973 __u32 *fh = vfh; 1974 __u64 inum = fh[2]; 1975 inum = (inum << 32) | fh[1]; 1976 return ino->i_ino == inum && fh[0] == ino->i_generation; 1977} 1978 1979static struct dentry *shmem_get_dentry(struct super_block *sb, void *vfh) 1980{ 1981 struct dentry *de = NULL; 1982 struct inode *inode; 1983 __u32 *fh = vfh; 1984 __u64 inum = fh[2]; 1985 inum = (inum << 32) | fh[1]; 1986 1987 inode = ilookup5(sb, (unsigned long)(inum+fh[0]), shmem_match, vfh); 1988 if (inode) { 1989 de = d_find_alias(inode); 1990 iput(inode); 1991 } 1992 1993 return de? de: ERR_PTR(-ESTALE); 1994} 1995 1996static struct dentry *shmem_decode_fh(struct super_block *sb, __u32 *fh, 1997 int len, int type, 1998 int (*acceptable)(void *context, struct dentry *de), 1999 void *context) 2000{ 2001 if (len < 3) 2002 return ERR_PTR(-ESTALE); 2003 2004 return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable, 2005 context); 2006} 2007 2008static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2009 int connectable) 2010{ 2011 struct inode *inode = dentry->d_inode; 2012 2013 if (*len < 3) 2014 return 255; 2015 2016 if (hlist_unhashed(&inode->i_hash)) { 2017 /* Unfortunately insert_inode_hash is not idempotent, 2018 * so as we hash inodes here rather than at creation 2019 * time, we need a lock to ensure we only try 2020 * to do it once 2021 */ 2022 static DEFINE_SPINLOCK(lock); 2023 spin_lock(&lock); 2024 if (hlist_unhashed(&inode->i_hash)) 2025 __insert_inode_hash(inode, 2026 inode->i_ino + inode->i_generation); 2027 spin_unlock(&lock); 2028 } 2029 2030 fh[0] = inode->i_generation; 2031 fh[1] = inode->i_ino; 2032 fh[2] = ((__u64)inode->i_ino) >> 32; 2033 2034 *len = 3; 2035 return 1; 2036} 2037 2038static struct export_operations shmem_export_ops = { 2039 .get_parent = shmem_get_parent, 2040 .get_dentry = shmem_get_dentry, 2041 .encode_fh = shmem_encode_fh, 2042 .decode_fh = shmem_decode_fh, 2043}; 2044 2045static int shmem_parse_options(char *options, int *mode, uid_t *uid, 2046 gid_t *gid, unsigned long *blocks, unsigned long *inodes, 2047 int *policy, nodemask_t *policy_nodes) 2048{ 2049 char *this_char, *value, *rest; 2050 2051 while (options != NULL) { 2052 this_char = options; 2053 for (;;) { 2054 /* 2055 * NUL-terminate this option: unfortunately, 2056 * mount options form a comma-separated list, 2057 * but mpol's nodelist may also contain commas. 2058 */ 2059 options = strchr(options, ','); 2060 if (options == NULL) 2061 break; 2062 options++; 2063 if (!isdigit(*options)) { 2064 options[-1] = '\0'; 2065 break; 2066 } 2067 } 2068 if (!*this_char) 2069 continue; 2070 if ((value = strchr(this_char,'=')) != NULL) { 2071 *value++ = 0; 2072 } else { 2073 printk(KERN_ERR 2074 "tmpfs: No value for mount option '%s'\n", 2075 this_char); 2076 return 1; 2077 } 2078 2079 if (!strcmp(this_char,"size")) { 2080 unsigned long long size; 2081 size = memparse(value,&rest); 2082 if (*rest == '%') { 2083 size <<= PAGE_SHIFT; 2084 size *= totalram_pages; 2085 do_div(size, 100); 2086 rest++; 2087 } 2088 if (*rest) 2089 goto bad_val; 2090 *blocks = size >> PAGE_CACHE_SHIFT; 2091 } else if (!strcmp(this_char,"nr_blocks")) { 2092 *blocks = memparse(value,&rest); 2093 if (*rest) 2094 goto bad_val; 2095 } else if (!strcmp(this_char,"nr_inodes")) { 2096 *inodes = memparse(value,&rest); 2097 if (*rest) 2098 goto bad_val; 2099 } else if (!strcmp(this_char,"mode")) { 2100 if (!mode) 2101 continue; 2102 *mode = simple_strtoul(value,&rest,8); 2103 if (*rest) 2104 goto bad_val; 2105 } else if (!strcmp(this_char,"uid")) { 2106 if (!uid) 2107 continue; 2108 *uid = simple_strtoul(value,&rest,0); 2109 if (*rest) 2110 goto bad_val; 2111 } else if (!strcmp(this_char,"gid")) { 2112 if (!gid) 2113 continue; 2114 *gid = simple_strtoul(value,&rest,0); 2115 if (*rest) 2116 goto bad_val; 2117 } else if (!strcmp(this_char,"mpol")) { 2118 if (shmem_parse_mpol(value,policy,policy_nodes)) 2119 goto bad_val; 2120 } else { 2121 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2122 this_char); 2123 return 1; 2124 } 2125 } 2126 return 0; 2127 2128bad_val: 2129 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2130 value, this_char); 2131 return 1; 2132 2133} 2134 2135static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2136{ 2137 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2138 unsigned long max_blocks = sbinfo->max_blocks; 2139 unsigned long max_inodes = sbinfo->max_inodes; 2140 int policy = sbinfo->policy; 2141 nodemask_t policy_nodes = sbinfo->policy_nodes; 2142 unsigned long blocks; 2143 unsigned long inodes; 2144 int error = -EINVAL; 2145 2146 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, 2147 &max_inodes, &policy, &policy_nodes)) 2148 return error; 2149 2150 spin_lock(&sbinfo->stat_lock); 2151 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2152 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2153 if (max_blocks < blocks) 2154 goto out; 2155 if (max_inodes < inodes) 2156 goto out; 2157 /* 2158 * Those tests also disallow limited->unlimited while any are in 2159 * use, so i_blocks will always be zero when max_blocks is zero; 2160 * but we must separately disallow unlimited->limited, because 2161 * in that case we have no record of how much is already in use. 2162 */ 2163 if (max_blocks && !sbinfo->max_blocks) 2164 goto out; 2165 if (max_inodes && !sbinfo->max_inodes) 2166 goto out; 2167 2168 error = 0; 2169 sbinfo->max_blocks = max_blocks; 2170 sbinfo->free_blocks = max_blocks - blocks; 2171 sbinfo->max_inodes = max_inodes; 2172 sbinfo->free_inodes = max_inodes - inodes; 2173 sbinfo->policy = policy; 2174 sbinfo->policy_nodes = policy_nodes; 2175out: 2176 spin_unlock(&sbinfo->stat_lock); 2177 return error; 2178} 2179#endif 2180 2181static void shmem_put_super(struct super_block *sb) 2182{ 2183 kfree(sb->s_fs_info); 2184 sb->s_fs_info = NULL; 2185} 2186 2187static int shmem_fill_super(struct super_block *sb, 2188 void *data, int silent) 2189{ 2190 struct inode *inode; 2191 struct dentry *root; 2192 int mode = S_IRWXUGO | S_ISVTX; 2193 uid_t uid = current->fsuid; 2194 gid_t gid = current->fsgid; 2195 int err = -ENOMEM; 2196 struct shmem_sb_info *sbinfo; 2197 unsigned long blocks = 0; 2198 unsigned long inodes = 0; 2199 int policy = MPOL_DEFAULT; 2200 nodemask_t policy_nodes = node_online_map; 2201 2202#ifdef CONFIG_TMPFS 2203 /* 2204 * Per default we only allow half of the physical ram per 2205 * tmpfs instance, limiting inodes to one per page of lowmem; 2206 * but the internal instance is left unlimited. 2207 */ 2208 if (!(sb->s_flags & MS_NOUSER)) { 2209 blocks = totalram_pages / 2; 2210 inodes = totalram_pages - totalhigh_pages; 2211 if (inodes > blocks) 2212 inodes = blocks; 2213 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, 2214 &inodes, &policy, &policy_nodes)) 2215 return -EINVAL; 2216 } 2217 sb->s_export_op = &shmem_export_ops; 2218#else 2219 sb->s_flags |= MS_NOUSER; 2220#endif 2221 2222 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2223 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 2224 L1_CACHE_BYTES), GFP_KERNEL); 2225 if (!sbinfo) 2226 return -ENOMEM; 2227 2228 spin_lock_init(&sbinfo->stat_lock); 2229 sbinfo->max_blocks = blocks; 2230 sbinfo->free_blocks = blocks; 2231 sbinfo->max_inodes = inodes; 2232 sbinfo->free_inodes = inodes; 2233 sbinfo->policy = policy; 2234 sbinfo->policy_nodes = policy_nodes; 2235 2236 sb->s_fs_info = sbinfo; 2237 sb->s_maxbytes = SHMEM_MAX_BYTES; 2238 sb->s_blocksize = PAGE_CACHE_SIZE; 2239 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2240 sb->s_magic = TMPFS_MAGIC; 2241 sb->s_op = &shmem_ops; 2242 sb->s_time_gran = 1; 2243#ifdef CONFIG_TMPFS_POSIX_ACL 2244 sb->s_xattr = shmem_xattr_handlers; 2245 sb->s_flags |= MS_POSIXACL; 2246#endif 2247 2248 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 2249 if (!inode) 2250 goto failed; 2251 inode->i_uid = uid; 2252 inode->i_gid = gid; 2253 root = d_alloc_root(inode); 2254 if (!root) 2255 goto failed_iput; 2256 sb->s_root = root; 2257 return 0; 2258 2259failed_iput: 2260 iput(inode); 2261failed: 2262 shmem_put_super(sb); 2263 return err; 2264} 2265 2266static struct kmem_cache *shmem_inode_cachep; 2267 2268static struct inode *shmem_alloc_inode(struct super_block *sb) 2269{ 2270 struct shmem_inode_info *p; 2271 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, GFP_KERNEL); 2272 if (!p) 2273 return NULL; 2274 return &p->vfs_inode; 2275} 2276 2277static void shmem_destroy_inode(struct inode *inode) 2278{ 2279 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2280 /* only struct inode is valid if it's an inline symlink */ 2281 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2282 } 2283 shmem_acl_destroy_inode(inode); 2284 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2285} 2286 2287static void init_once(void *foo, struct kmem_cache *cachep, 2288 unsigned long flags) 2289{ 2290 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2291 2292 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == 2293 SLAB_CTOR_CONSTRUCTOR) { 2294 inode_init_once(&p->vfs_inode); 2295#ifdef CONFIG_TMPFS_POSIX_ACL 2296 p->i_acl = NULL; 2297 p->i_default_acl = NULL; 2298#endif 2299 } 2300} 2301 2302static int init_inodecache(void) 2303{ 2304 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2305 sizeof(struct shmem_inode_info), 2306 0, 0, init_once, NULL); 2307 if (shmem_inode_cachep == NULL) 2308 return -ENOMEM; 2309 return 0; 2310} 2311 2312static void destroy_inodecache(void) 2313{ 2314 kmem_cache_destroy(shmem_inode_cachep); 2315} 2316 2317static const struct address_space_operations shmem_aops = { 2318 .writepage = shmem_writepage, 2319 .set_page_dirty = __set_page_dirty_nobuffers, 2320#ifdef CONFIG_TMPFS 2321 .prepare_write = shmem_prepare_write, 2322 .commit_write = simple_commit_write, 2323#endif 2324 .migratepage = migrate_page, 2325}; 2326 2327static const struct file_operations shmem_file_operations = { 2328 .mmap = shmem_mmap, 2329#ifdef CONFIG_TMPFS 2330 .llseek = generic_file_llseek, 2331 .read = shmem_file_read, 2332 .write = shmem_file_write, 2333 .fsync = simple_sync_file, 2334 .sendfile = shmem_file_sendfile, 2335#endif 2336}; 2337 2338static struct inode_operations shmem_inode_operations = { 2339 .truncate = shmem_truncate, 2340 .setattr = shmem_notify_change, 2341 .truncate_range = shmem_truncate_range, 2342#ifdef CONFIG_TMPFS_POSIX_ACL 2343 .setxattr = generic_setxattr, 2344 .getxattr = generic_getxattr, 2345 .listxattr = generic_listxattr, 2346 .removexattr = generic_removexattr, 2347 .permission = shmem_permission, 2348#endif 2349 2350}; 2351 2352static struct inode_operations shmem_dir_inode_operations = { 2353#ifdef CONFIG_TMPFS 2354 .create = shmem_create, 2355 .lookup = simple_lookup, 2356 .link = shmem_link, 2357 .unlink = shmem_unlink, 2358 .symlink = shmem_symlink, 2359 .mkdir = shmem_mkdir, 2360 .rmdir = shmem_rmdir, 2361 .mknod = shmem_mknod, 2362 .rename = shmem_rename, 2363#endif 2364#ifdef CONFIG_TMPFS_POSIX_ACL 2365 .setattr = shmem_notify_change, 2366 .setxattr = generic_setxattr, 2367 .getxattr = generic_getxattr, 2368 .listxattr = generic_listxattr, 2369 .removexattr = generic_removexattr, 2370 .permission = shmem_permission, 2371#endif 2372}; 2373 2374static struct inode_operations shmem_special_inode_operations = { 2375#ifdef CONFIG_TMPFS_POSIX_ACL 2376 .setattr = shmem_notify_change, 2377 .setxattr = generic_setxattr, 2378 .getxattr = generic_getxattr, 2379 .listxattr = generic_listxattr, 2380 .removexattr = generic_removexattr, 2381 .permission = shmem_permission, 2382#endif 2383}; 2384 2385static struct super_operations shmem_ops = { 2386 .alloc_inode = shmem_alloc_inode, 2387 .destroy_inode = shmem_destroy_inode, 2388#ifdef CONFIG_TMPFS 2389 .statfs = shmem_statfs, 2390 .remount_fs = shmem_remount_fs, 2391#endif 2392 .delete_inode = shmem_delete_inode, 2393 .drop_inode = generic_delete_inode, 2394 .put_super = shmem_put_super, 2395}; 2396 2397static struct vm_operations_struct shmem_vm_ops = { 2398 .nopage = shmem_nopage, 2399 .populate = shmem_populate, 2400#ifdef CONFIG_NUMA 2401 .set_policy = shmem_set_policy, 2402 .get_policy = shmem_get_policy, 2403#endif 2404}; 2405 2406 2407static int shmem_get_sb(struct file_system_type *fs_type, 2408 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2409{ 2410 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2411} 2412 2413static struct file_system_type tmpfs_fs_type = { 2414 .owner = THIS_MODULE, 2415 .name = "tmpfs", 2416 .get_sb = shmem_get_sb, 2417 .kill_sb = kill_litter_super, 2418}; 2419static struct vfsmount *shm_mnt; 2420 2421static int __init init_tmpfs(void) 2422{ 2423 int error; 2424 2425 error = init_inodecache(); 2426 if (error) 2427 goto out3; 2428 2429 error = register_filesystem(&tmpfs_fs_type); 2430 if (error) { 2431 printk(KERN_ERR "Could not register tmpfs\n"); 2432 goto out2; 2433 } 2434 2435 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2436 tmpfs_fs_type.name, NULL); 2437 if (IS_ERR(shm_mnt)) { 2438 error = PTR_ERR(shm_mnt); 2439 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2440 goto out1; 2441 } 2442 return 0; 2443 2444out1: 2445 unregister_filesystem(&tmpfs_fs_type); 2446out2: 2447 destroy_inodecache(); 2448out3: 2449 shm_mnt = ERR_PTR(error); 2450 return error; 2451} 2452module_init(init_tmpfs) 2453 2454/* 2455 * shmem_file_setup - get an unlinked file living in tmpfs 2456 * 2457 * @name: name for dentry (to be seen in /proc/<pid>/maps 2458 * @size: size to be set for the file 2459 * 2460 */ 2461struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2462{ 2463 int error; 2464 struct file *file; 2465 struct inode *inode; 2466 struct dentry *dentry, *root; 2467 struct qstr this; 2468 2469 if (IS_ERR(shm_mnt)) 2470 return (void *)shm_mnt; 2471 2472 if (size < 0 || size > SHMEM_MAX_BYTES) 2473 return ERR_PTR(-EINVAL); 2474 2475 if (shmem_acct_size(flags, size)) 2476 return ERR_PTR(-ENOMEM); 2477 2478 error = -ENOMEM; 2479 this.name = name; 2480 this.len = strlen(name); 2481 this.hash = 0; /* will go */ 2482 root = shm_mnt->mnt_root; 2483 dentry = d_alloc(root, &this); 2484 if (!dentry) 2485 goto put_memory; 2486 2487 error = -ENFILE; 2488 file = get_empty_filp(); 2489 if (!file) 2490 goto put_dentry; 2491 2492 error = -ENOSPC; 2493 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2494 if (!inode) 2495 goto close_file; 2496 2497 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2498 d_instantiate(dentry, inode); 2499 inode->i_size = size; 2500 inode->i_nlink = 0; /* It is unlinked */ 2501 file->f_path.mnt = mntget(shm_mnt); 2502 file->f_path.dentry = dentry; 2503 file->f_mapping = inode->i_mapping; 2504 file->f_op = &shmem_file_operations; 2505 file->f_mode = FMODE_WRITE | FMODE_READ; 2506 return file; 2507 2508close_file: 2509 put_filp(file); 2510put_dentry: 2511 dput(dentry); 2512put_memory: 2513 shmem_unacct_size(flags, size); 2514 return ERR_PTR(error); 2515} 2516 2517/* 2518 * shmem_zero_setup - setup a shared anonymous mapping 2519 * 2520 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2521 */ 2522int shmem_zero_setup(struct vm_area_struct *vma) 2523{ 2524 struct file *file; 2525 loff_t size = vma->vm_end - vma->vm_start; 2526 2527 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2528 if (IS_ERR(file)) 2529 return PTR_ERR(file); 2530 2531 if (vma->vm_file) 2532 fput(vma->vm_file); 2533 vma->vm_file = file; 2534 vma->vm_ops = &shmem_vm_ops; 2535 return 0; 2536} 2537