shmem.c revision 91828a405ae454a9503c41a7744f6ff877a80714
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 52#include <asm/uaccess.h> 53#include <asm/div64.h> 54#include <asm/pgtable.h> 55 56/* This magic number is used in glibc for posix shared memory */ 57#define TMPFS_MAGIC 0x01021994 58 59#define ENTRIES_PER_PAGE (PAGE_CACHE_SIZE/sizeof(unsigned long)) 60#define ENTRIES_PER_PAGEPAGE (ENTRIES_PER_PAGE*ENTRIES_PER_PAGE) 61#define BLOCKS_PER_PAGE (PAGE_CACHE_SIZE/512) 62 63#define SHMEM_MAX_INDEX (SHMEM_NR_DIRECT + (ENTRIES_PER_PAGEPAGE/2) * (ENTRIES_PER_PAGE+1)) 64#define SHMEM_MAX_BYTES ((unsigned long long)SHMEM_MAX_INDEX << PAGE_CACHE_SHIFT) 65 66#define VM_ACCT(size) (PAGE_CACHE_ALIGN(size) >> PAGE_SHIFT) 67 68/* info->flags needs VM_flags to handle pagein/truncate races efficiently */ 69#define SHMEM_PAGEIN VM_READ 70#define SHMEM_TRUNCATE VM_WRITE 71 72/* Definition to limit shmem_truncate's steps between cond_rescheds */ 73#define LATENCY_LIMIT 64 74 75/* Pretend that each entry is of this size in directory's i_size */ 76#define BOGO_DIRENT_SIZE 20 77 78/* Flag allocation requirements to shmem_getpage and shmem_swp_alloc */ 79enum sgp_type { 80 SGP_QUICK, /* don't try more than file page cache lookup */ 81 SGP_READ, /* don't exceed i_size, don't allocate page */ 82 SGP_CACHE, /* don't exceed i_size, may allocate page */ 83 SGP_WRITE, /* may exceed i_size, may allocate page */ 84}; 85 86static int shmem_getpage(struct inode *inode, unsigned long idx, 87 struct page **pagep, enum sgp_type sgp, int *type); 88 89static inline struct page *shmem_dir_alloc(gfp_t gfp_mask) 90{ 91 /* 92 * The above definition of ENTRIES_PER_PAGE, and the use of 93 * BLOCKS_PER_PAGE on indirect pages, assume PAGE_CACHE_SIZE: 94 * might be reconsidered if it ever diverges from PAGE_SIZE. 95 */ 96 return alloc_pages(gfp_mask, PAGE_CACHE_SHIFT-PAGE_SHIFT); 97} 98 99static inline void shmem_dir_free(struct page *page) 100{ 101 __free_pages(page, PAGE_CACHE_SHIFT-PAGE_SHIFT); 102} 103 104static struct page **shmem_dir_map(struct page *page) 105{ 106 return (struct page **)kmap_atomic(page, KM_USER0); 107} 108 109static inline void shmem_dir_unmap(struct page **dir) 110{ 111 kunmap_atomic(dir, KM_USER0); 112} 113 114static swp_entry_t *shmem_swp_map(struct page *page) 115{ 116 return (swp_entry_t *)kmap_atomic(page, KM_USER1); 117} 118 119static inline void shmem_swp_balance_unmap(void) 120{ 121 /* 122 * When passing a pointer to an i_direct entry, to code which 123 * also handles indirect entries and so will shmem_swp_unmap, 124 * we must arrange for the preempt count to remain in balance. 125 * What kmap_atomic of a lowmem page does depends on config 126 * and architecture, so pretend to kmap_atomic some lowmem page. 127 */ 128 (void) kmap_atomic(ZERO_PAGE(0), KM_USER1); 129} 130 131static inline void shmem_swp_unmap(swp_entry_t *entry) 132{ 133 kunmap_atomic(entry, KM_USER1); 134} 135 136static inline struct shmem_sb_info *SHMEM_SB(struct super_block *sb) 137{ 138 return sb->s_fs_info; 139} 140 141/* 142 * shmem_file_setup pre-accounts the whole fixed size of a VM object, 143 * for shared memory and for shared anonymous (/dev/zero) mappings 144 * (unless MAP_NORESERVE and sysctl_overcommit_memory <= 1), 145 * consistent with the pre-accounting of private mappings ... 146 */ 147static inline int shmem_acct_size(unsigned long flags, loff_t size) 148{ 149 return (flags & VM_ACCOUNT)? 150 security_vm_enough_memory(VM_ACCT(size)): 0; 151} 152 153static inline void shmem_unacct_size(unsigned long flags, loff_t size) 154{ 155 if (flags & VM_ACCOUNT) 156 vm_unacct_memory(VM_ACCT(size)); 157} 158 159/* 160 * ... whereas tmpfs objects are accounted incrementally as 161 * pages are allocated, in order to allow huge sparse files. 162 * shmem_getpage reports shmem_acct_block failure as -ENOSPC not -ENOMEM, 163 * so that a failure on a sparse tmpfs mapping will give SIGBUS not OOM. 164 */ 165static inline int shmem_acct_block(unsigned long flags) 166{ 167 return (flags & VM_ACCOUNT)? 168 0: security_vm_enough_memory(VM_ACCT(PAGE_CACHE_SIZE)); 169} 170 171static inline void shmem_unacct_blocks(unsigned long flags, long pages) 172{ 173 if (!(flags & VM_ACCOUNT)) 174 vm_unacct_memory(pages * VM_ACCT(PAGE_CACHE_SIZE)); 175} 176 177static struct super_operations shmem_ops; 178static const struct address_space_operations shmem_aops; 179static struct file_operations shmem_file_operations; 180static struct inode_operations shmem_inode_operations; 181static struct inode_operations shmem_dir_inode_operations; 182static struct inode_operations shmem_special_inode_operations; 183static struct vm_operations_struct shmem_vm_ops; 184 185static struct backing_dev_info shmem_backing_dev_info __read_mostly = { 186 .ra_pages = 0, /* No readahead */ 187 .capabilities = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK, 188 .unplug_io_fn = default_unplug_io_fn, 189}; 190 191static LIST_HEAD(shmem_swaplist); 192static DEFINE_SPINLOCK(shmem_swaplist_lock); 193 194static void shmem_free_blocks(struct inode *inode, long pages) 195{ 196 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 197 if (sbinfo->max_blocks) { 198 spin_lock(&sbinfo->stat_lock); 199 sbinfo->free_blocks += pages; 200 inode->i_blocks -= pages*BLOCKS_PER_PAGE; 201 spin_unlock(&sbinfo->stat_lock); 202 } 203} 204 205/* 206 * shmem_recalc_inode - recalculate the size of an inode 207 * 208 * @inode: inode to recalc 209 * 210 * We have to calculate the free blocks since the mm can drop 211 * undirtied hole pages behind our back. 212 * 213 * But normally info->alloced == inode->i_mapping->nrpages + info->swapped 214 * So mm freed is info->alloced - (inode->i_mapping->nrpages + info->swapped) 215 * 216 * It has to be called with the spinlock held. 217 */ 218static void shmem_recalc_inode(struct inode *inode) 219{ 220 struct shmem_inode_info *info = SHMEM_I(inode); 221 long freed; 222 223 freed = info->alloced - info->swapped - inode->i_mapping->nrpages; 224 if (freed > 0) { 225 info->alloced -= freed; 226 shmem_unacct_blocks(info->flags, freed); 227 shmem_free_blocks(inode, freed); 228 } 229} 230 231/* 232 * shmem_swp_entry - find the swap vector position in the info structure 233 * 234 * @info: info structure for the inode 235 * @index: index of the page to find 236 * @page: optional page to add to the structure. Has to be preset to 237 * all zeros 238 * 239 * If there is no space allocated yet it will return NULL when 240 * page is NULL, else it will use the page for the needed block, 241 * setting it to NULL on return to indicate that it has been used. 242 * 243 * The swap vector is organized the following way: 244 * 245 * There are SHMEM_NR_DIRECT entries directly stored in the 246 * shmem_inode_info structure. So small files do not need an addional 247 * allocation. 248 * 249 * For pages with index > SHMEM_NR_DIRECT there is the pointer 250 * i_indirect which points to a page which holds in the first half 251 * doubly indirect blocks, in the second half triple indirect blocks: 252 * 253 * For an artificial ENTRIES_PER_PAGE = 4 this would lead to the 254 * following layout (for SHMEM_NR_DIRECT == 16): 255 * 256 * i_indirect -> dir --> 16-19 257 * | +-> 20-23 258 * | 259 * +-->dir2 --> 24-27 260 * | +-> 28-31 261 * | +-> 32-35 262 * | +-> 36-39 263 * | 264 * +-->dir3 --> 40-43 265 * +-> 44-47 266 * +-> 48-51 267 * +-> 52-55 268 */ 269static swp_entry_t *shmem_swp_entry(struct shmem_inode_info *info, unsigned long index, struct page **page) 270{ 271 unsigned long offset; 272 struct page **dir; 273 struct page *subdir; 274 275 if (index < SHMEM_NR_DIRECT) { 276 shmem_swp_balance_unmap(); 277 return info->i_direct+index; 278 } 279 if (!info->i_indirect) { 280 if (page) { 281 info->i_indirect = *page; 282 *page = NULL; 283 } 284 return NULL; /* need another page */ 285 } 286 287 index -= SHMEM_NR_DIRECT; 288 offset = index % ENTRIES_PER_PAGE; 289 index /= ENTRIES_PER_PAGE; 290 dir = shmem_dir_map(info->i_indirect); 291 292 if (index >= ENTRIES_PER_PAGE/2) { 293 index -= ENTRIES_PER_PAGE/2; 294 dir += ENTRIES_PER_PAGE/2 + index/ENTRIES_PER_PAGE; 295 index %= ENTRIES_PER_PAGE; 296 subdir = *dir; 297 if (!subdir) { 298 if (page) { 299 *dir = *page; 300 *page = NULL; 301 } 302 shmem_dir_unmap(dir); 303 return NULL; /* need another page */ 304 } 305 shmem_dir_unmap(dir); 306 dir = shmem_dir_map(subdir); 307 } 308 309 dir += index; 310 subdir = *dir; 311 if (!subdir) { 312 if (!page || !(subdir = *page)) { 313 shmem_dir_unmap(dir); 314 return NULL; /* need a page */ 315 } 316 *dir = subdir; 317 *page = NULL; 318 } 319 shmem_dir_unmap(dir); 320 return shmem_swp_map(subdir) + offset; 321} 322 323static void shmem_swp_set(struct shmem_inode_info *info, swp_entry_t *entry, unsigned long value) 324{ 325 long incdec = value? 1: -1; 326 327 entry->val = value; 328 info->swapped += incdec; 329 if ((unsigned long)(entry - info->i_direct) >= SHMEM_NR_DIRECT) { 330 struct page *page = kmap_atomic_to_page(entry); 331 set_page_private(page, page_private(page) + incdec); 332 } 333} 334 335/* 336 * shmem_swp_alloc - get the position of the swap entry for the page. 337 * If it does not exist allocate the entry. 338 * 339 * @info: info structure for the inode 340 * @index: index of the page to find 341 * @sgp: check and recheck i_size? skip allocation? 342 */ 343static swp_entry_t *shmem_swp_alloc(struct shmem_inode_info *info, unsigned long index, enum sgp_type sgp) 344{ 345 struct inode *inode = &info->vfs_inode; 346 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 347 struct page *page = NULL; 348 swp_entry_t *entry; 349 350 if (sgp != SGP_WRITE && 351 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 352 return ERR_PTR(-EINVAL); 353 354 while (!(entry = shmem_swp_entry(info, index, &page))) { 355 if (sgp == SGP_READ) 356 return shmem_swp_map(ZERO_PAGE(0)); 357 /* 358 * Test free_blocks against 1 not 0, since we have 1 data 359 * page (and perhaps indirect index pages) yet to allocate: 360 * a waste to allocate index if we cannot allocate data. 361 */ 362 if (sbinfo->max_blocks) { 363 spin_lock(&sbinfo->stat_lock); 364 if (sbinfo->free_blocks <= 1) { 365 spin_unlock(&sbinfo->stat_lock); 366 return ERR_PTR(-ENOSPC); 367 } 368 sbinfo->free_blocks--; 369 inode->i_blocks += BLOCKS_PER_PAGE; 370 spin_unlock(&sbinfo->stat_lock); 371 } 372 373 spin_unlock(&info->lock); 374 page = shmem_dir_alloc(mapping_gfp_mask(inode->i_mapping) | __GFP_ZERO); 375 if (page) 376 set_page_private(page, 0); 377 spin_lock(&info->lock); 378 379 if (!page) { 380 shmem_free_blocks(inode, 1); 381 return ERR_PTR(-ENOMEM); 382 } 383 if (sgp != SGP_WRITE && 384 ((loff_t) index << PAGE_CACHE_SHIFT) >= i_size_read(inode)) { 385 entry = ERR_PTR(-EINVAL); 386 break; 387 } 388 if (info->next_index <= index) 389 info->next_index = index + 1; 390 } 391 if (page) { 392 /* another task gave its page, or truncated the file */ 393 shmem_free_blocks(inode, 1); 394 shmem_dir_free(page); 395 } 396 if (info->next_index <= index && !IS_ERR(entry)) 397 info->next_index = index + 1; 398 return entry; 399} 400 401/* 402 * shmem_free_swp - free some swap entries in a directory 403 * 404 * @dir: pointer to the directory 405 * @edir: pointer after last entry of the directory 406 */ 407static int shmem_free_swp(swp_entry_t *dir, swp_entry_t *edir) 408{ 409 swp_entry_t *ptr; 410 int freed = 0; 411 412 for (ptr = dir; ptr < edir; ptr++) { 413 if (ptr->val) { 414 free_swap_and_cache(*ptr); 415 *ptr = (swp_entry_t){0}; 416 freed++; 417 } 418 } 419 return freed; 420} 421 422static int shmem_map_and_free_swp(struct page *subdir, 423 int offset, int limit, struct page ***dir) 424{ 425 swp_entry_t *ptr; 426 int freed = 0; 427 428 ptr = shmem_swp_map(subdir); 429 for (; offset < limit; offset += LATENCY_LIMIT) { 430 int size = limit - offset; 431 if (size > LATENCY_LIMIT) 432 size = LATENCY_LIMIT; 433 freed += shmem_free_swp(ptr+offset, ptr+offset+size); 434 if (need_resched()) { 435 shmem_swp_unmap(ptr); 436 if (*dir) { 437 shmem_dir_unmap(*dir); 438 *dir = NULL; 439 } 440 cond_resched(); 441 ptr = shmem_swp_map(subdir); 442 } 443 } 444 shmem_swp_unmap(ptr); 445 return freed; 446} 447 448static void shmem_free_pages(struct list_head *next) 449{ 450 struct page *page; 451 int freed = 0; 452 453 do { 454 page = container_of(next, struct page, lru); 455 next = next->next; 456 shmem_dir_free(page); 457 freed++; 458 if (freed >= LATENCY_LIMIT) { 459 cond_resched(); 460 freed = 0; 461 } 462 } while (next); 463} 464 465static void shmem_truncate_range(struct inode *inode, loff_t start, loff_t end) 466{ 467 struct shmem_inode_info *info = SHMEM_I(inode); 468 unsigned long idx; 469 unsigned long size; 470 unsigned long limit; 471 unsigned long stage; 472 unsigned long diroff; 473 struct page **dir; 474 struct page *topdir; 475 struct page *middir; 476 struct page *subdir; 477 swp_entry_t *ptr; 478 LIST_HEAD(pages_to_free); 479 long nr_pages_to_free = 0; 480 long nr_swaps_freed = 0; 481 int offset; 482 int freed; 483 int punch_hole = 0; 484 485 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 486 idx = (start + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 487 if (idx >= info->next_index) 488 return; 489 490 spin_lock(&info->lock); 491 info->flags |= SHMEM_TRUNCATE; 492 if (likely(end == (loff_t) -1)) { 493 limit = info->next_index; 494 info->next_index = idx; 495 } else { 496 limit = (end + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; 497 if (limit > info->next_index) 498 limit = info->next_index; 499 punch_hole = 1; 500 } 501 502 topdir = info->i_indirect; 503 if (topdir && idx <= SHMEM_NR_DIRECT && !punch_hole) { 504 info->i_indirect = NULL; 505 nr_pages_to_free++; 506 list_add(&topdir->lru, &pages_to_free); 507 } 508 spin_unlock(&info->lock); 509 510 if (info->swapped && idx < SHMEM_NR_DIRECT) { 511 ptr = info->i_direct; 512 size = limit; 513 if (size > SHMEM_NR_DIRECT) 514 size = SHMEM_NR_DIRECT; 515 nr_swaps_freed = shmem_free_swp(ptr+idx, ptr+size); 516 } 517 if (!topdir) 518 goto done2; 519 520 BUG_ON(limit <= SHMEM_NR_DIRECT); 521 limit -= SHMEM_NR_DIRECT; 522 idx = (idx > SHMEM_NR_DIRECT)? (idx - SHMEM_NR_DIRECT): 0; 523 offset = idx % ENTRIES_PER_PAGE; 524 idx -= offset; 525 526 dir = shmem_dir_map(topdir); 527 stage = ENTRIES_PER_PAGEPAGE/2; 528 if (idx < ENTRIES_PER_PAGEPAGE/2) { 529 middir = topdir; 530 diroff = idx/ENTRIES_PER_PAGE; 531 } else { 532 dir += ENTRIES_PER_PAGE/2; 533 dir += (idx - ENTRIES_PER_PAGEPAGE/2)/ENTRIES_PER_PAGEPAGE; 534 while (stage <= idx) 535 stage += ENTRIES_PER_PAGEPAGE; 536 middir = *dir; 537 if (*dir) { 538 diroff = ((idx - ENTRIES_PER_PAGEPAGE/2) % 539 ENTRIES_PER_PAGEPAGE) / ENTRIES_PER_PAGE; 540 if (!diroff && !offset) { 541 *dir = NULL; 542 nr_pages_to_free++; 543 list_add(&middir->lru, &pages_to_free); 544 } 545 shmem_dir_unmap(dir); 546 dir = shmem_dir_map(middir); 547 } else { 548 diroff = 0; 549 offset = 0; 550 idx = stage; 551 } 552 } 553 554 for (; idx < limit; idx += ENTRIES_PER_PAGE, diroff++) { 555 if (unlikely(idx == stage)) { 556 shmem_dir_unmap(dir); 557 dir = shmem_dir_map(topdir) + 558 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 559 while (!*dir) { 560 dir++; 561 idx += ENTRIES_PER_PAGEPAGE; 562 if (idx >= limit) 563 goto done1; 564 } 565 stage = idx + ENTRIES_PER_PAGEPAGE; 566 middir = *dir; 567 *dir = NULL; 568 nr_pages_to_free++; 569 list_add(&middir->lru, &pages_to_free); 570 shmem_dir_unmap(dir); 571 cond_resched(); 572 dir = shmem_dir_map(middir); 573 diroff = 0; 574 } 575 subdir = dir[diroff]; 576 if (subdir && page_private(subdir)) { 577 size = limit - idx; 578 if (size > ENTRIES_PER_PAGE) 579 size = ENTRIES_PER_PAGE; 580 freed = shmem_map_and_free_swp(subdir, 581 offset, size, &dir); 582 if (!dir) 583 dir = shmem_dir_map(middir); 584 nr_swaps_freed += freed; 585 if (offset) 586 spin_lock(&info->lock); 587 set_page_private(subdir, page_private(subdir) - freed); 588 if (offset) 589 spin_unlock(&info->lock); 590 if (!punch_hole) 591 BUG_ON(page_private(subdir) > offset); 592 } 593 if (offset) 594 offset = 0; 595 else if (subdir && !page_private(subdir)) { 596 dir[diroff] = NULL; 597 nr_pages_to_free++; 598 list_add(&subdir->lru, &pages_to_free); 599 } 600 } 601done1: 602 shmem_dir_unmap(dir); 603done2: 604 if (inode->i_mapping->nrpages && (info->flags & SHMEM_PAGEIN)) { 605 /* 606 * Call truncate_inode_pages again: racing shmem_unuse_inode 607 * may have swizzled a page in from swap since vmtruncate or 608 * generic_delete_inode did it, before we lowered next_index. 609 * Also, though shmem_getpage checks i_size before adding to 610 * cache, no recheck after: so fix the narrow window there too. 611 */ 612 truncate_inode_pages_range(inode->i_mapping, start, end); 613 } 614 615 spin_lock(&info->lock); 616 info->flags &= ~SHMEM_TRUNCATE; 617 info->swapped -= nr_swaps_freed; 618 if (nr_pages_to_free) 619 shmem_free_blocks(inode, nr_pages_to_free); 620 shmem_recalc_inode(inode); 621 spin_unlock(&info->lock); 622 623 /* 624 * Empty swap vector directory pages to be freed? 625 */ 626 if (!list_empty(&pages_to_free)) { 627 pages_to_free.prev->next = NULL; 628 shmem_free_pages(pages_to_free.next); 629 } 630} 631 632static void shmem_truncate(struct inode *inode) 633{ 634 shmem_truncate_range(inode, inode->i_size, (loff_t)-1); 635} 636 637static int shmem_notify_change(struct dentry *dentry, struct iattr *attr) 638{ 639 struct inode *inode = dentry->d_inode; 640 struct page *page = NULL; 641 int error; 642 643 if (S_ISREG(inode->i_mode) && (attr->ia_valid & ATTR_SIZE)) { 644 if (attr->ia_size < inode->i_size) { 645 /* 646 * If truncating down to a partial page, then 647 * if that page is already allocated, hold it 648 * in memory until the truncation is over, so 649 * truncate_partial_page cannnot miss it were 650 * it assigned to swap. 651 */ 652 if (attr->ia_size & (PAGE_CACHE_SIZE-1)) { 653 (void) shmem_getpage(inode, 654 attr->ia_size>>PAGE_CACHE_SHIFT, 655 &page, SGP_READ, NULL); 656 } 657 /* 658 * Reset SHMEM_PAGEIN flag so that shmem_truncate can 659 * detect if any pages might have been added to cache 660 * after truncate_inode_pages. But we needn't bother 661 * if it's being fully truncated to zero-length: the 662 * nrpages check is efficient enough in that case. 663 */ 664 if (attr->ia_size) { 665 struct shmem_inode_info *info = SHMEM_I(inode); 666 spin_lock(&info->lock); 667 info->flags &= ~SHMEM_PAGEIN; 668 spin_unlock(&info->lock); 669 } 670 } 671 } 672 673 error = inode_change_ok(inode, attr); 674 if (!error) 675 error = inode_setattr(inode, attr); 676#ifdef CONFIG_TMPFS_POSIX_ACL 677 if (!error && (attr->ia_valid & ATTR_MODE)) 678 error = generic_acl_chmod(inode, &shmem_acl_ops); 679#endif 680 if (page) 681 page_cache_release(page); 682 return error; 683} 684 685static void shmem_delete_inode(struct inode *inode) 686{ 687 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 688 struct shmem_inode_info *info = SHMEM_I(inode); 689 690 if (inode->i_op->truncate == shmem_truncate) { 691 truncate_inode_pages(inode->i_mapping, 0); 692 shmem_unacct_size(info->flags, inode->i_size); 693 inode->i_size = 0; 694 shmem_truncate(inode); 695 if (!list_empty(&info->swaplist)) { 696 spin_lock(&shmem_swaplist_lock); 697 list_del_init(&info->swaplist); 698 spin_unlock(&shmem_swaplist_lock); 699 } 700 } 701 BUG_ON(inode->i_blocks); 702 if (sbinfo->max_inodes) { 703 spin_lock(&sbinfo->stat_lock); 704 sbinfo->free_inodes++; 705 spin_unlock(&sbinfo->stat_lock); 706 } 707 clear_inode(inode); 708} 709 710static inline int shmem_find_swp(swp_entry_t entry, swp_entry_t *dir, swp_entry_t *edir) 711{ 712 swp_entry_t *ptr; 713 714 for (ptr = dir; ptr < edir; ptr++) { 715 if (ptr->val == entry.val) 716 return ptr - dir; 717 } 718 return -1; 719} 720 721static int shmem_unuse_inode(struct shmem_inode_info *info, swp_entry_t entry, struct page *page) 722{ 723 struct inode *inode; 724 unsigned long idx; 725 unsigned long size; 726 unsigned long limit; 727 unsigned long stage; 728 struct page **dir; 729 struct page *subdir; 730 swp_entry_t *ptr; 731 int offset; 732 733 idx = 0; 734 ptr = info->i_direct; 735 spin_lock(&info->lock); 736 limit = info->next_index; 737 size = limit; 738 if (size > SHMEM_NR_DIRECT) 739 size = SHMEM_NR_DIRECT; 740 offset = shmem_find_swp(entry, ptr, ptr+size); 741 if (offset >= 0) { 742 shmem_swp_balance_unmap(); 743 goto found; 744 } 745 if (!info->i_indirect) 746 goto lost2; 747 748 dir = shmem_dir_map(info->i_indirect); 749 stage = SHMEM_NR_DIRECT + ENTRIES_PER_PAGEPAGE/2; 750 751 for (idx = SHMEM_NR_DIRECT; idx < limit; idx += ENTRIES_PER_PAGE, dir++) { 752 if (unlikely(idx == stage)) { 753 shmem_dir_unmap(dir-1); 754 dir = shmem_dir_map(info->i_indirect) + 755 ENTRIES_PER_PAGE/2 + idx/ENTRIES_PER_PAGEPAGE; 756 while (!*dir) { 757 dir++; 758 idx += ENTRIES_PER_PAGEPAGE; 759 if (idx >= limit) 760 goto lost1; 761 } 762 stage = idx + ENTRIES_PER_PAGEPAGE; 763 subdir = *dir; 764 shmem_dir_unmap(dir); 765 dir = shmem_dir_map(subdir); 766 } 767 subdir = *dir; 768 if (subdir && page_private(subdir)) { 769 ptr = shmem_swp_map(subdir); 770 size = limit - idx; 771 if (size > ENTRIES_PER_PAGE) 772 size = ENTRIES_PER_PAGE; 773 offset = shmem_find_swp(entry, ptr, ptr+size); 774 if (offset >= 0) { 775 shmem_dir_unmap(dir); 776 goto found; 777 } 778 shmem_swp_unmap(ptr); 779 } 780 } 781lost1: 782 shmem_dir_unmap(dir-1); 783lost2: 784 spin_unlock(&info->lock); 785 return 0; 786found: 787 idx += offset; 788 inode = &info->vfs_inode; 789 if (move_from_swap_cache(page, idx, inode->i_mapping) == 0) { 790 info->flags |= SHMEM_PAGEIN; 791 shmem_swp_set(info, ptr + offset, 0); 792 } 793 shmem_swp_unmap(ptr); 794 spin_unlock(&info->lock); 795 /* 796 * Decrement swap count even when the entry is left behind: 797 * try_to_unuse will skip over mms, then reincrement count. 798 */ 799 swap_free(entry); 800 return 1; 801} 802 803/* 804 * shmem_unuse() search for an eventually swapped out shmem page. 805 */ 806int shmem_unuse(swp_entry_t entry, struct page *page) 807{ 808 struct list_head *p, *next; 809 struct shmem_inode_info *info; 810 int found = 0; 811 812 spin_lock(&shmem_swaplist_lock); 813 list_for_each_safe(p, next, &shmem_swaplist) { 814 info = list_entry(p, struct shmem_inode_info, swaplist); 815 if (!info->swapped) 816 list_del_init(&info->swaplist); 817 else if (shmem_unuse_inode(info, entry, page)) { 818 /* move head to start search for next from here */ 819 list_move_tail(&shmem_swaplist, &info->swaplist); 820 found = 1; 821 break; 822 } 823 } 824 spin_unlock(&shmem_swaplist_lock); 825 return found; 826} 827 828/* 829 * Move the page from the page cache to the swap cache. 830 */ 831static int shmem_writepage(struct page *page, struct writeback_control *wbc) 832{ 833 struct shmem_inode_info *info; 834 swp_entry_t *entry, swap; 835 struct address_space *mapping; 836 unsigned long index; 837 struct inode *inode; 838 839 BUG_ON(!PageLocked(page)); 840 BUG_ON(page_mapped(page)); 841 842 mapping = page->mapping; 843 index = page->index; 844 inode = mapping->host; 845 info = SHMEM_I(inode); 846 if (info->flags & VM_LOCKED) 847 goto redirty; 848 swap = get_swap_page(); 849 if (!swap.val) 850 goto redirty; 851 852 spin_lock(&info->lock); 853 shmem_recalc_inode(inode); 854 if (index >= info->next_index) { 855 BUG_ON(!(info->flags & SHMEM_TRUNCATE)); 856 goto unlock; 857 } 858 entry = shmem_swp_entry(info, index, NULL); 859 BUG_ON(!entry); 860 BUG_ON(entry->val); 861 862 if (move_to_swap_cache(page, swap) == 0) { 863 shmem_swp_set(info, entry, swap.val); 864 shmem_swp_unmap(entry); 865 spin_unlock(&info->lock); 866 if (list_empty(&info->swaplist)) { 867 spin_lock(&shmem_swaplist_lock); 868 /* move instead of add in case we're racing */ 869 list_move_tail(&info->swaplist, &shmem_swaplist); 870 spin_unlock(&shmem_swaplist_lock); 871 } 872 unlock_page(page); 873 return 0; 874 } 875 876 shmem_swp_unmap(entry); 877unlock: 878 spin_unlock(&info->lock); 879 swap_free(swap); 880redirty: 881 set_page_dirty(page); 882 return AOP_WRITEPAGE_ACTIVATE; /* Return with the page locked */ 883} 884 885#ifdef CONFIG_NUMA 886static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 887{ 888 char *nodelist = strchr(value, ':'); 889 int err = 1; 890 891 if (nodelist) { 892 /* NUL-terminate policy string */ 893 *nodelist++ = '\0'; 894 if (nodelist_parse(nodelist, *policy_nodes)) 895 goto out; 896 } 897 if (!strcmp(value, "default")) { 898 *policy = MPOL_DEFAULT; 899 /* Don't allow a nodelist */ 900 if (!nodelist) 901 err = 0; 902 } else if (!strcmp(value, "prefer")) { 903 *policy = MPOL_PREFERRED; 904 /* Insist on a nodelist of one node only */ 905 if (nodelist) { 906 char *rest = nodelist; 907 while (isdigit(*rest)) 908 rest++; 909 if (!*rest) 910 err = 0; 911 } 912 } else if (!strcmp(value, "bind")) { 913 *policy = MPOL_BIND; 914 /* Insist on a nodelist */ 915 if (nodelist) 916 err = 0; 917 } else if (!strcmp(value, "interleave")) { 918 *policy = MPOL_INTERLEAVE; 919 /* Default to nodes online if no nodelist */ 920 if (!nodelist) 921 *policy_nodes = node_online_map; 922 err = 0; 923 } 924out: 925 /* Restore string for error message */ 926 if (nodelist) 927 *--nodelist = ':'; 928 return err; 929} 930 931static struct page *shmem_swapin_async(struct shared_policy *p, 932 swp_entry_t entry, unsigned long idx) 933{ 934 struct page *page; 935 struct vm_area_struct pvma; 936 937 /* Create a pseudo vma that just contains the policy */ 938 memset(&pvma, 0, sizeof(struct vm_area_struct)); 939 pvma.vm_end = PAGE_SIZE; 940 pvma.vm_pgoff = idx; 941 pvma.vm_policy = mpol_shared_policy_lookup(p, idx); 942 page = read_swap_cache_async(entry, &pvma, 0); 943 mpol_free(pvma.vm_policy); 944 return page; 945} 946 947struct page *shmem_swapin(struct shmem_inode_info *info, swp_entry_t entry, 948 unsigned long idx) 949{ 950 struct shared_policy *p = &info->policy; 951 int i, num; 952 struct page *page; 953 unsigned long offset; 954 955 num = valid_swaphandles(entry, &offset); 956 for (i = 0; i < num; offset++, i++) { 957 page = shmem_swapin_async(p, 958 swp_entry(swp_type(entry), offset), idx); 959 if (!page) 960 break; 961 page_cache_release(page); 962 } 963 lru_add_drain(); /* Push any new pages onto the LRU now */ 964 return shmem_swapin_async(p, entry, idx); 965} 966 967static struct page * 968shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, 969 unsigned long idx) 970{ 971 struct vm_area_struct pvma; 972 struct page *page; 973 974 memset(&pvma, 0, sizeof(struct vm_area_struct)); 975 pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, idx); 976 pvma.vm_pgoff = idx; 977 pvma.vm_end = PAGE_SIZE; 978 page = alloc_page_vma(gfp | __GFP_ZERO, &pvma, 0); 979 mpol_free(pvma.vm_policy); 980 return page; 981} 982#else 983static inline int shmem_parse_mpol(char *value, int *policy, nodemask_t *policy_nodes) 984{ 985 return 1; 986} 987 988static inline struct page * 989shmem_swapin(struct shmem_inode_info *info,swp_entry_t entry,unsigned long idx) 990{ 991 swapin_readahead(entry, 0, NULL); 992 return read_swap_cache_async(entry, NULL, 0); 993} 994 995static inline struct page * 996shmem_alloc_page(gfp_t gfp,struct shmem_inode_info *info, unsigned long idx) 997{ 998 return alloc_page(gfp | __GFP_ZERO); 999} 1000#endif 1001 1002/* 1003 * shmem_getpage - either get the page from swap or allocate a new one 1004 * 1005 * If we allocate a new one we do not mark it dirty. That's up to the 1006 * vm. If we swap it in we mark it dirty since we also free the swap 1007 * entry since a page cannot live in both the swap and page cache 1008 */ 1009static int shmem_getpage(struct inode *inode, unsigned long idx, 1010 struct page **pagep, enum sgp_type sgp, int *type) 1011{ 1012 struct address_space *mapping = inode->i_mapping; 1013 struct shmem_inode_info *info = SHMEM_I(inode); 1014 struct shmem_sb_info *sbinfo; 1015 struct page *filepage = *pagep; 1016 struct page *swappage; 1017 swp_entry_t *entry; 1018 swp_entry_t swap; 1019 int error; 1020 1021 if (idx >= SHMEM_MAX_INDEX) 1022 return -EFBIG; 1023 /* 1024 * Normally, filepage is NULL on entry, and either found 1025 * uptodate immediately, or allocated and zeroed, or read 1026 * in under swappage, which is then assigned to filepage. 1027 * But shmem_prepare_write passes in a locked filepage, 1028 * which may be found not uptodate by other callers too, 1029 * and may need to be copied from the swappage read in. 1030 */ 1031repeat: 1032 if (!filepage) 1033 filepage = find_lock_page(mapping, idx); 1034 if (filepage && PageUptodate(filepage)) 1035 goto done; 1036 error = 0; 1037 if (sgp == SGP_QUICK) 1038 goto failed; 1039 1040 spin_lock(&info->lock); 1041 shmem_recalc_inode(inode); 1042 entry = shmem_swp_alloc(info, idx, sgp); 1043 if (IS_ERR(entry)) { 1044 spin_unlock(&info->lock); 1045 error = PTR_ERR(entry); 1046 goto failed; 1047 } 1048 swap = *entry; 1049 1050 if (swap.val) { 1051 /* Look it up and read it in.. */ 1052 swappage = lookup_swap_cache(swap); 1053 if (!swappage) { 1054 shmem_swp_unmap(entry); 1055 /* here we actually do the io */ 1056 if (type && *type == VM_FAULT_MINOR) { 1057 __count_vm_event(PGMAJFAULT); 1058 *type = VM_FAULT_MAJOR; 1059 } 1060 spin_unlock(&info->lock); 1061 swappage = shmem_swapin(info, swap, idx); 1062 if (!swappage) { 1063 spin_lock(&info->lock); 1064 entry = shmem_swp_alloc(info, idx, sgp); 1065 if (IS_ERR(entry)) 1066 error = PTR_ERR(entry); 1067 else { 1068 if (entry->val == swap.val) 1069 error = -ENOMEM; 1070 shmem_swp_unmap(entry); 1071 } 1072 spin_unlock(&info->lock); 1073 if (error) 1074 goto failed; 1075 goto repeat; 1076 } 1077 wait_on_page_locked(swappage); 1078 page_cache_release(swappage); 1079 goto repeat; 1080 } 1081 1082 /* We have to do this with page locked to prevent races */ 1083 if (TestSetPageLocked(swappage)) { 1084 shmem_swp_unmap(entry); 1085 spin_unlock(&info->lock); 1086 wait_on_page_locked(swappage); 1087 page_cache_release(swappage); 1088 goto repeat; 1089 } 1090 if (PageWriteback(swappage)) { 1091 shmem_swp_unmap(entry); 1092 spin_unlock(&info->lock); 1093 wait_on_page_writeback(swappage); 1094 unlock_page(swappage); 1095 page_cache_release(swappage); 1096 goto repeat; 1097 } 1098 if (!PageUptodate(swappage)) { 1099 shmem_swp_unmap(entry); 1100 spin_unlock(&info->lock); 1101 unlock_page(swappage); 1102 page_cache_release(swappage); 1103 error = -EIO; 1104 goto failed; 1105 } 1106 1107 if (filepage) { 1108 shmem_swp_set(info, entry, 0); 1109 shmem_swp_unmap(entry); 1110 delete_from_swap_cache(swappage); 1111 spin_unlock(&info->lock); 1112 copy_highpage(filepage, swappage); 1113 unlock_page(swappage); 1114 page_cache_release(swappage); 1115 flush_dcache_page(filepage); 1116 SetPageUptodate(filepage); 1117 set_page_dirty(filepage); 1118 swap_free(swap); 1119 } else if (!(error = move_from_swap_cache( 1120 swappage, idx, mapping))) { 1121 info->flags |= SHMEM_PAGEIN; 1122 shmem_swp_set(info, entry, 0); 1123 shmem_swp_unmap(entry); 1124 spin_unlock(&info->lock); 1125 filepage = swappage; 1126 swap_free(swap); 1127 } else { 1128 shmem_swp_unmap(entry); 1129 spin_unlock(&info->lock); 1130 unlock_page(swappage); 1131 page_cache_release(swappage); 1132 if (error == -ENOMEM) { 1133 /* let kswapd refresh zone for GFP_ATOMICs */ 1134 blk_congestion_wait(WRITE, HZ/50); 1135 } 1136 goto repeat; 1137 } 1138 } else if (sgp == SGP_READ && !filepage) { 1139 shmem_swp_unmap(entry); 1140 filepage = find_get_page(mapping, idx); 1141 if (filepage && 1142 (!PageUptodate(filepage) || TestSetPageLocked(filepage))) { 1143 spin_unlock(&info->lock); 1144 wait_on_page_locked(filepage); 1145 page_cache_release(filepage); 1146 filepage = NULL; 1147 goto repeat; 1148 } 1149 spin_unlock(&info->lock); 1150 } else { 1151 shmem_swp_unmap(entry); 1152 sbinfo = SHMEM_SB(inode->i_sb); 1153 if (sbinfo->max_blocks) { 1154 spin_lock(&sbinfo->stat_lock); 1155 if (sbinfo->free_blocks == 0 || 1156 shmem_acct_block(info->flags)) { 1157 spin_unlock(&sbinfo->stat_lock); 1158 spin_unlock(&info->lock); 1159 error = -ENOSPC; 1160 goto failed; 1161 } 1162 sbinfo->free_blocks--; 1163 inode->i_blocks += BLOCKS_PER_PAGE; 1164 spin_unlock(&sbinfo->stat_lock); 1165 } else if (shmem_acct_block(info->flags)) { 1166 spin_unlock(&info->lock); 1167 error = -ENOSPC; 1168 goto failed; 1169 } 1170 1171 if (!filepage) { 1172 spin_unlock(&info->lock); 1173 filepage = shmem_alloc_page(mapping_gfp_mask(mapping), 1174 info, 1175 idx); 1176 if (!filepage) { 1177 shmem_unacct_blocks(info->flags, 1); 1178 shmem_free_blocks(inode, 1); 1179 error = -ENOMEM; 1180 goto failed; 1181 } 1182 1183 spin_lock(&info->lock); 1184 entry = shmem_swp_alloc(info, idx, sgp); 1185 if (IS_ERR(entry)) 1186 error = PTR_ERR(entry); 1187 else { 1188 swap = *entry; 1189 shmem_swp_unmap(entry); 1190 } 1191 if (error || swap.val || 0 != add_to_page_cache_lru( 1192 filepage, mapping, idx, GFP_ATOMIC)) { 1193 spin_unlock(&info->lock); 1194 page_cache_release(filepage); 1195 shmem_unacct_blocks(info->flags, 1); 1196 shmem_free_blocks(inode, 1); 1197 filepage = NULL; 1198 if (error) 1199 goto failed; 1200 goto repeat; 1201 } 1202 info->flags |= SHMEM_PAGEIN; 1203 } 1204 1205 info->alloced++; 1206 spin_unlock(&info->lock); 1207 flush_dcache_page(filepage); 1208 SetPageUptodate(filepage); 1209 } 1210done: 1211 if (*pagep != filepage) { 1212 unlock_page(filepage); 1213 *pagep = filepage; 1214 } 1215 return 0; 1216 1217failed: 1218 if (*pagep != filepage) { 1219 unlock_page(filepage); 1220 page_cache_release(filepage); 1221 } 1222 return error; 1223} 1224 1225struct page *shmem_nopage(struct vm_area_struct *vma, unsigned long address, int *type) 1226{ 1227 struct inode *inode = vma->vm_file->f_dentry->d_inode; 1228 struct page *page = NULL; 1229 unsigned long idx; 1230 int error; 1231 1232 idx = (address - vma->vm_start) >> PAGE_SHIFT; 1233 idx += vma->vm_pgoff; 1234 idx >>= PAGE_CACHE_SHIFT - PAGE_SHIFT; 1235 if (((loff_t) idx << PAGE_CACHE_SHIFT) >= i_size_read(inode)) 1236 return NOPAGE_SIGBUS; 1237 1238 error = shmem_getpage(inode, idx, &page, SGP_CACHE, type); 1239 if (error) 1240 return (error == -ENOMEM)? NOPAGE_OOM: NOPAGE_SIGBUS; 1241 1242 mark_page_accessed(page); 1243 return page; 1244} 1245 1246static int shmem_populate(struct vm_area_struct *vma, 1247 unsigned long addr, unsigned long len, 1248 pgprot_t prot, unsigned long pgoff, int nonblock) 1249{ 1250 struct inode *inode = vma->vm_file->f_dentry->d_inode; 1251 struct mm_struct *mm = vma->vm_mm; 1252 enum sgp_type sgp = nonblock? SGP_QUICK: SGP_CACHE; 1253 unsigned long size; 1254 1255 size = (i_size_read(inode) + PAGE_SIZE - 1) >> PAGE_SHIFT; 1256 if (pgoff >= size || pgoff + (len >> PAGE_SHIFT) > size) 1257 return -EINVAL; 1258 1259 while ((long) len > 0) { 1260 struct page *page = NULL; 1261 int err; 1262 /* 1263 * Will need changing if PAGE_CACHE_SIZE != PAGE_SIZE 1264 */ 1265 err = shmem_getpage(inode, pgoff, &page, sgp, NULL); 1266 if (err) 1267 return err; 1268 /* Page may still be null, but only if nonblock was set. */ 1269 if (page) { 1270 mark_page_accessed(page); 1271 err = install_page(mm, vma, addr, page, prot); 1272 if (err) { 1273 page_cache_release(page); 1274 return err; 1275 } 1276 } else if (vma->vm_flags & VM_NONLINEAR) { 1277 /* No page was found just because we can't read it in 1278 * now (being here implies nonblock != 0), but the page 1279 * may exist, so set the PTE to fault it in later. */ 1280 err = install_file_pte(mm, vma, addr, pgoff, prot); 1281 if (err) 1282 return err; 1283 } 1284 1285 len -= PAGE_SIZE; 1286 addr += PAGE_SIZE; 1287 pgoff++; 1288 } 1289 return 0; 1290} 1291 1292#ifdef CONFIG_NUMA 1293int shmem_set_policy(struct vm_area_struct *vma, struct mempolicy *new) 1294{ 1295 struct inode *i = vma->vm_file->f_dentry->d_inode; 1296 return mpol_set_shared_policy(&SHMEM_I(i)->policy, vma, new); 1297} 1298 1299struct mempolicy * 1300shmem_get_policy(struct vm_area_struct *vma, unsigned long addr) 1301{ 1302 struct inode *i = vma->vm_file->f_dentry->d_inode; 1303 unsigned long idx; 1304 1305 idx = ((addr - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; 1306 return mpol_shared_policy_lookup(&SHMEM_I(i)->policy, idx); 1307} 1308#endif 1309 1310int shmem_lock(struct file *file, int lock, struct user_struct *user) 1311{ 1312 struct inode *inode = file->f_dentry->d_inode; 1313 struct shmem_inode_info *info = SHMEM_I(inode); 1314 int retval = -ENOMEM; 1315 1316 spin_lock(&info->lock); 1317 if (lock && !(info->flags & VM_LOCKED)) { 1318 if (!user_shm_lock(inode->i_size, user)) 1319 goto out_nomem; 1320 info->flags |= VM_LOCKED; 1321 } 1322 if (!lock && (info->flags & VM_LOCKED) && user) { 1323 user_shm_unlock(inode->i_size, user); 1324 info->flags &= ~VM_LOCKED; 1325 } 1326 retval = 0; 1327out_nomem: 1328 spin_unlock(&info->lock); 1329 return retval; 1330} 1331 1332int shmem_mmap(struct file *file, struct vm_area_struct *vma) 1333{ 1334 file_accessed(file); 1335 vma->vm_ops = &shmem_vm_ops; 1336 return 0; 1337} 1338 1339static struct inode * 1340shmem_get_inode(struct super_block *sb, int mode, dev_t dev) 1341{ 1342 struct inode *inode; 1343 struct shmem_inode_info *info; 1344 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 1345 1346 if (sbinfo->max_inodes) { 1347 spin_lock(&sbinfo->stat_lock); 1348 if (!sbinfo->free_inodes) { 1349 spin_unlock(&sbinfo->stat_lock); 1350 return NULL; 1351 } 1352 sbinfo->free_inodes--; 1353 spin_unlock(&sbinfo->stat_lock); 1354 } 1355 1356 inode = new_inode(sb); 1357 if (inode) { 1358 inode->i_mode = mode; 1359 inode->i_uid = current->fsuid; 1360 inode->i_gid = current->fsgid; 1361 inode->i_blocks = 0; 1362 inode->i_mapping->a_ops = &shmem_aops; 1363 inode->i_mapping->backing_dev_info = &shmem_backing_dev_info; 1364 inode->i_atime = inode->i_mtime = inode->i_ctime = CURRENT_TIME; 1365 inode->i_generation = get_seconds(); 1366 info = SHMEM_I(inode); 1367 memset(info, 0, (char *)inode - (char *)info); 1368 spin_lock_init(&info->lock); 1369 INIT_LIST_HEAD(&info->swaplist); 1370 1371 switch (mode & S_IFMT) { 1372 default: 1373 inode->i_op = &shmem_special_inode_operations; 1374 init_special_inode(inode, mode, dev); 1375 break; 1376 case S_IFREG: 1377 inode->i_op = &shmem_inode_operations; 1378 inode->i_fop = &shmem_file_operations; 1379 mpol_shared_policy_init(&info->policy, sbinfo->policy, 1380 &sbinfo->policy_nodes); 1381 break; 1382 case S_IFDIR: 1383 inc_nlink(inode); 1384 /* Some things misbehave if size == 0 on a directory */ 1385 inode->i_size = 2 * BOGO_DIRENT_SIZE; 1386 inode->i_op = &shmem_dir_inode_operations; 1387 inode->i_fop = &simple_dir_operations; 1388 break; 1389 case S_IFLNK: 1390 /* 1391 * Must not load anything in the rbtree, 1392 * mpol_free_shared_policy will not be called. 1393 */ 1394 mpol_shared_policy_init(&info->policy, MPOL_DEFAULT, 1395 NULL); 1396 break; 1397 } 1398 } else if (sbinfo->max_inodes) { 1399 spin_lock(&sbinfo->stat_lock); 1400 sbinfo->free_inodes++; 1401 spin_unlock(&sbinfo->stat_lock); 1402 } 1403 return inode; 1404} 1405 1406#ifdef CONFIG_TMPFS 1407static struct inode_operations shmem_symlink_inode_operations; 1408static struct inode_operations shmem_symlink_inline_operations; 1409 1410/* 1411 * Normally tmpfs makes no use of shmem_prepare_write, but it 1412 * lets a tmpfs file be used read-write below the loop driver. 1413 */ 1414static int 1415shmem_prepare_write(struct file *file, struct page *page, unsigned offset, unsigned to) 1416{ 1417 struct inode *inode = page->mapping->host; 1418 return shmem_getpage(inode, page->index, &page, SGP_WRITE, NULL); 1419} 1420 1421static ssize_t 1422shmem_file_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) 1423{ 1424 struct inode *inode = file->f_dentry->d_inode; 1425 loff_t pos; 1426 unsigned long written; 1427 ssize_t err; 1428 1429 if ((ssize_t) count < 0) 1430 return -EINVAL; 1431 1432 if (!access_ok(VERIFY_READ, buf, count)) 1433 return -EFAULT; 1434 1435 mutex_lock(&inode->i_mutex); 1436 1437 pos = *ppos; 1438 written = 0; 1439 1440 err = generic_write_checks(file, &pos, &count, 0); 1441 if (err || !count) 1442 goto out; 1443 1444 err = remove_suid(file->f_dentry); 1445 if (err) 1446 goto out; 1447 1448 inode->i_ctime = inode->i_mtime = CURRENT_TIME; 1449 1450 do { 1451 struct page *page = NULL; 1452 unsigned long bytes, index, offset; 1453 char *kaddr; 1454 int left; 1455 1456 offset = (pos & (PAGE_CACHE_SIZE -1)); /* Within page */ 1457 index = pos >> PAGE_CACHE_SHIFT; 1458 bytes = PAGE_CACHE_SIZE - offset; 1459 if (bytes > count) 1460 bytes = count; 1461 1462 /* 1463 * We don't hold page lock across copy from user - 1464 * what would it guard against? - so no deadlock here. 1465 * But it still may be a good idea to prefault below. 1466 */ 1467 1468 err = shmem_getpage(inode, index, &page, SGP_WRITE, NULL); 1469 if (err) 1470 break; 1471 1472 left = bytes; 1473 if (PageHighMem(page)) { 1474 volatile unsigned char dummy; 1475 __get_user(dummy, buf); 1476 __get_user(dummy, buf + bytes - 1); 1477 1478 kaddr = kmap_atomic(page, KM_USER0); 1479 left = __copy_from_user_inatomic(kaddr + offset, 1480 buf, bytes); 1481 kunmap_atomic(kaddr, KM_USER0); 1482 } 1483 if (left) { 1484 kaddr = kmap(page); 1485 left = __copy_from_user(kaddr + offset, buf, bytes); 1486 kunmap(page); 1487 } 1488 1489 written += bytes; 1490 count -= bytes; 1491 pos += bytes; 1492 buf += bytes; 1493 if (pos > inode->i_size) 1494 i_size_write(inode, pos); 1495 1496 flush_dcache_page(page); 1497 set_page_dirty(page); 1498 mark_page_accessed(page); 1499 page_cache_release(page); 1500 1501 if (left) { 1502 pos -= left; 1503 written -= left; 1504 err = -EFAULT; 1505 break; 1506 } 1507 1508 /* 1509 * Our dirty pages are not counted in nr_dirty, 1510 * and we do not attempt to balance dirty pages. 1511 */ 1512 1513 cond_resched(); 1514 } while (count); 1515 1516 *ppos = pos; 1517 if (written) 1518 err = written; 1519out: 1520 mutex_unlock(&inode->i_mutex); 1521 return err; 1522} 1523 1524static void do_shmem_file_read(struct file *filp, loff_t *ppos, read_descriptor_t *desc, read_actor_t actor) 1525{ 1526 struct inode *inode = filp->f_dentry->d_inode; 1527 struct address_space *mapping = inode->i_mapping; 1528 unsigned long index, offset; 1529 1530 index = *ppos >> PAGE_CACHE_SHIFT; 1531 offset = *ppos & ~PAGE_CACHE_MASK; 1532 1533 for (;;) { 1534 struct page *page = NULL; 1535 unsigned long end_index, nr, ret; 1536 loff_t i_size = i_size_read(inode); 1537 1538 end_index = i_size >> PAGE_CACHE_SHIFT; 1539 if (index > end_index) 1540 break; 1541 if (index == end_index) { 1542 nr = i_size & ~PAGE_CACHE_MASK; 1543 if (nr <= offset) 1544 break; 1545 } 1546 1547 desc->error = shmem_getpage(inode, index, &page, SGP_READ, NULL); 1548 if (desc->error) { 1549 if (desc->error == -EINVAL) 1550 desc->error = 0; 1551 break; 1552 } 1553 1554 /* 1555 * We must evaluate after, since reads (unlike writes) 1556 * are called without i_mutex protection against truncate 1557 */ 1558 nr = PAGE_CACHE_SIZE; 1559 i_size = i_size_read(inode); 1560 end_index = i_size >> PAGE_CACHE_SHIFT; 1561 if (index == end_index) { 1562 nr = i_size & ~PAGE_CACHE_MASK; 1563 if (nr <= offset) { 1564 if (page) 1565 page_cache_release(page); 1566 break; 1567 } 1568 } 1569 nr -= offset; 1570 1571 if (page) { 1572 /* 1573 * If users can be writing to this page using arbitrary 1574 * virtual addresses, take care about potential aliasing 1575 * before reading the page on the kernel side. 1576 */ 1577 if (mapping_writably_mapped(mapping)) 1578 flush_dcache_page(page); 1579 /* 1580 * Mark the page accessed if we read the beginning. 1581 */ 1582 if (!offset) 1583 mark_page_accessed(page); 1584 } else { 1585 page = ZERO_PAGE(0); 1586 page_cache_get(page); 1587 } 1588 1589 /* 1590 * Ok, we have the page, and it's up-to-date, so 1591 * now we can copy it to user space... 1592 * 1593 * The actor routine returns how many bytes were actually used.. 1594 * NOTE! This may not be the same as how much of a user buffer 1595 * we filled up (we may be padding etc), so we can only update 1596 * "pos" here (the actor routine has to update the user buffer 1597 * pointers and the remaining count). 1598 */ 1599 ret = actor(desc, page, offset, nr); 1600 offset += ret; 1601 index += offset >> PAGE_CACHE_SHIFT; 1602 offset &= ~PAGE_CACHE_MASK; 1603 1604 page_cache_release(page); 1605 if (ret != nr || !desc->count) 1606 break; 1607 1608 cond_resched(); 1609 } 1610 1611 *ppos = ((loff_t) index << PAGE_CACHE_SHIFT) + offset; 1612 file_accessed(filp); 1613} 1614 1615static ssize_t shmem_file_read(struct file *filp, char __user *buf, size_t count, loff_t *ppos) 1616{ 1617 read_descriptor_t desc; 1618 1619 if ((ssize_t) count < 0) 1620 return -EINVAL; 1621 if (!access_ok(VERIFY_WRITE, buf, count)) 1622 return -EFAULT; 1623 if (!count) 1624 return 0; 1625 1626 desc.written = 0; 1627 desc.count = count; 1628 desc.arg.buf = buf; 1629 desc.error = 0; 1630 1631 do_shmem_file_read(filp, ppos, &desc, file_read_actor); 1632 if (desc.written) 1633 return desc.written; 1634 return desc.error; 1635} 1636 1637static ssize_t shmem_file_sendfile(struct file *in_file, loff_t *ppos, 1638 size_t count, read_actor_t actor, void *target) 1639{ 1640 read_descriptor_t desc; 1641 1642 if (!count) 1643 return 0; 1644 1645 desc.written = 0; 1646 desc.count = count; 1647 desc.arg.data = target; 1648 desc.error = 0; 1649 1650 do_shmem_file_read(in_file, ppos, &desc, actor); 1651 if (desc.written) 1652 return desc.written; 1653 return desc.error; 1654} 1655 1656static int shmem_statfs(struct dentry *dentry, struct kstatfs *buf) 1657{ 1658 struct shmem_sb_info *sbinfo = SHMEM_SB(dentry->d_sb); 1659 1660 buf->f_type = TMPFS_MAGIC; 1661 buf->f_bsize = PAGE_CACHE_SIZE; 1662 buf->f_namelen = NAME_MAX; 1663 spin_lock(&sbinfo->stat_lock); 1664 if (sbinfo->max_blocks) { 1665 buf->f_blocks = sbinfo->max_blocks; 1666 buf->f_bavail = buf->f_bfree = sbinfo->free_blocks; 1667 } 1668 if (sbinfo->max_inodes) { 1669 buf->f_files = sbinfo->max_inodes; 1670 buf->f_ffree = sbinfo->free_inodes; 1671 } 1672 /* else leave those fields 0 like simple_statfs */ 1673 spin_unlock(&sbinfo->stat_lock); 1674 return 0; 1675} 1676 1677/* 1678 * File creation. Allocate an inode, and we're done.. 1679 */ 1680static int 1681shmem_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev) 1682{ 1683 struct inode *inode = shmem_get_inode(dir->i_sb, mode, dev); 1684 int error = -ENOSPC; 1685 1686 if (inode) { 1687 error = security_inode_init_security(inode, dir, NULL, NULL, 1688 NULL); 1689 if (error) { 1690 if (error != -EOPNOTSUPP) { 1691 iput(inode); 1692 return error; 1693 } 1694 } 1695 error = shmem_acl_init(inode, dir); 1696 if (error) { 1697 iput(inode); 1698 return error; 1699 } 1700 if (dir->i_mode & S_ISGID) { 1701 inode->i_gid = dir->i_gid; 1702 if (S_ISDIR(mode)) 1703 inode->i_mode |= S_ISGID; 1704 } 1705 dir->i_size += BOGO_DIRENT_SIZE; 1706 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1707 d_instantiate(dentry, inode); 1708 dget(dentry); /* Extra count - pin the dentry in core */ 1709 } 1710 return error; 1711} 1712 1713static int shmem_mkdir(struct inode *dir, struct dentry *dentry, int mode) 1714{ 1715 int error; 1716 1717 if ((error = shmem_mknod(dir, dentry, mode | S_IFDIR, 0))) 1718 return error; 1719 inc_nlink(dir); 1720 return 0; 1721} 1722 1723static int shmem_create(struct inode *dir, struct dentry *dentry, int mode, 1724 struct nameidata *nd) 1725{ 1726 return shmem_mknod(dir, dentry, mode | S_IFREG, 0); 1727} 1728 1729/* 1730 * Link a file.. 1731 */ 1732static int shmem_link(struct dentry *old_dentry, struct inode *dir, struct dentry *dentry) 1733{ 1734 struct inode *inode = old_dentry->d_inode; 1735 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1736 1737 /* 1738 * No ordinary (disk based) filesystem counts links as inodes; 1739 * but each new link needs a new dentry, pinning lowmem, and 1740 * tmpfs dentries cannot be pruned until they are unlinked. 1741 */ 1742 if (sbinfo->max_inodes) { 1743 spin_lock(&sbinfo->stat_lock); 1744 if (!sbinfo->free_inodes) { 1745 spin_unlock(&sbinfo->stat_lock); 1746 return -ENOSPC; 1747 } 1748 sbinfo->free_inodes--; 1749 spin_unlock(&sbinfo->stat_lock); 1750 } 1751 1752 dir->i_size += BOGO_DIRENT_SIZE; 1753 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1754 inc_nlink(inode); 1755 atomic_inc(&inode->i_count); /* New dentry reference */ 1756 dget(dentry); /* Extra pinning count for the created dentry */ 1757 d_instantiate(dentry, inode); 1758 return 0; 1759} 1760 1761static int shmem_unlink(struct inode *dir, struct dentry *dentry) 1762{ 1763 struct inode *inode = dentry->d_inode; 1764 1765 if (inode->i_nlink > 1 && !S_ISDIR(inode->i_mode)) { 1766 struct shmem_sb_info *sbinfo = SHMEM_SB(inode->i_sb); 1767 if (sbinfo->max_inodes) { 1768 spin_lock(&sbinfo->stat_lock); 1769 sbinfo->free_inodes++; 1770 spin_unlock(&sbinfo->stat_lock); 1771 } 1772 } 1773 1774 dir->i_size -= BOGO_DIRENT_SIZE; 1775 inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1776 drop_nlink(inode); 1777 dput(dentry); /* Undo the count from "create" - this does all the work */ 1778 return 0; 1779} 1780 1781static int shmem_rmdir(struct inode *dir, struct dentry *dentry) 1782{ 1783 if (!simple_empty(dentry)) 1784 return -ENOTEMPTY; 1785 1786 drop_nlink(dentry->d_inode); 1787 drop_nlink(dir); 1788 return shmem_unlink(dir, dentry); 1789} 1790 1791/* 1792 * The VFS layer already does all the dentry stuff for rename, 1793 * we just have to decrement the usage count for the target if 1794 * it exists so that the VFS layer correctly free's it when it 1795 * gets overwritten. 1796 */ 1797static int shmem_rename(struct inode *old_dir, struct dentry *old_dentry, struct inode *new_dir, struct dentry *new_dentry) 1798{ 1799 struct inode *inode = old_dentry->d_inode; 1800 int they_are_dirs = S_ISDIR(inode->i_mode); 1801 1802 if (!simple_empty(new_dentry)) 1803 return -ENOTEMPTY; 1804 1805 if (new_dentry->d_inode) { 1806 (void) shmem_unlink(new_dir, new_dentry); 1807 if (they_are_dirs) 1808 drop_nlink(old_dir); 1809 } else if (they_are_dirs) { 1810 drop_nlink(old_dir); 1811 inc_nlink(new_dir); 1812 } 1813 1814 old_dir->i_size -= BOGO_DIRENT_SIZE; 1815 new_dir->i_size += BOGO_DIRENT_SIZE; 1816 old_dir->i_ctime = old_dir->i_mtime = 1817 new_dir->i_ctime = new_dir->i_mtime = 1818 inode->i_ctime = CURRENT_TIME; 1819 return 0; 1820} 1821 1822static int shmem_symlink(struct inode *dir, struct dentry *dentry, const char *symname) 1823{ 1824 int error; 1825 int len; 1826 struct inode *inode; 1827 struct page *page = NULL; 1828 char *kaddr; 1829 struct shmem_inode_info *info; 1830 1831 len = strlen(symname) + 1; 1832 if (len > PAGE_CACHE_SIZE) 1833 return -ENAMETOOLONG; 1834 1835 inode = shmem_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0); 1836 if (!inode) 1837 return -ENOSPC; 1838 1839 error = security_inode_init_security(inode, dir, NULL, NULL, 1840 NULL); 1841 if (error) { 1842 if (error != -EOPNOTSUPP) { 1843 iput(inode); 1844 return error; 1845 } 1846 error = 0; 1847 } 1848 1849 info = SHMEM_I(inode); 1850 inode->i_size = len-1; 1851 if (len <= (char *)inode - (char *)info) { 1852 /* do it inline */ 1853 memcpy(info, symname, len); 1854 inode->i_op = &shmem_symlink_inline_operations; 1855 } else { 1856 error = shmem_getpage(inode, 0, &page, SGP_WRITE, NULL); 1857 if (error) { 1858 iput(inode); 1859 return error; 1860 } 1861 inode->i_op = &shmem_symlink_inode_operations; 1862 kaddr = kmap_atomic(page, KM_USER0); 1863 memcpy(kaddr, symname, len); 1864 kunmap_atomic(kaddr, KM_USER0); 1865 set_page_dirty(page); 1866 page_cache_release(page); 1867 } 1868 if (dir->i_mode & S_ISGID) 1869 inode->i_gid = dir->i_gid; 1870 dir->i_size += BOGO_DIRENT_SIZE; 1871 dir->i_ctime = dir->i_mtime = CURRENT_TIME; 1872 d_instantiate(dentry, inode); 1873 dget(dentry); 1874 return 0; 1875} 1876 1877static void *shmem_follow_link_inline(struct dentry *dentry, struct nameidata *nd) 1878{ 1879 nd_set_link(nd, (char *)SHMEM_I(dentry->d_inode)); 1880 return NULL; 1881} 1882 1883static void *shmem_follow_link(struct dentry *dentry, struct nameidata *nd) 1884{ 1885 struct page *page = NULL; 1886 int res = shmem_getpage(dentry->d_inode, 0, &page, SGP_READ, NULL); 1887 nd_set_link(nd, res ? ERR_PTR(res) : kmap(page)); 1888 return page; 1889} 1890 1891static void shmem_put_link(struct dentry *dentry, struct nameidata *nd, void *cookie) 1892{ 1893 if (!IS_ERR(nd_get_link(nd))) { 1894 struct page *page = cookie; 1895 kunmap(page); 1896 mark_page_accessed(page); 1897 page_cache_release(page); 1898 } 1899} 1900 1901static struct inode_operations shmem_symlink_inline_operations = { 1902 .readlink = generic_readlink, 1903 .follow_link = shmem_follow_link_inline, 1904}; 1905 1906static struct inode_operations shmem_symlink_inode_operations = { 1907 .truncate = shmem_truncate, 1908 .readlink = generic_readlink, 1909 .follow_link = shmem_follow_link, 1910 .put_link = shmem_put_link, 1911}; 1912 1913#ifdef CONFIG_TMPFS_POSIX_ACL 1914/** 1915 * Superblocks without xattr inode operations will get security.* xattr 1916 * support from the VFS "for free". As soon as we have any other xattrs 1917 * like ACLs, we also need to implement the security.* handlers at 1918 * filesystem level, though. 1919 */ 1920 1921static size_t shmem_xattr_security_list(struct inode *inode, char *list, 1922 size_t list_len, const char *name, 1923 size_t name_len) 1924{ 1925 return security_inode_listsecurity(inode, list, list_len); 1926} 1927 1928static int shmem_xattr_security_get(struct inode *inode, const char *name, 1929 void *buffer, size_t size) 1930{ 1931 if (strcmp(name, "") == 0) 1932 return -EINVAL; 1933 return security_inode_getsecurity(inode, name, buffer, size, 1934 -EOPNOTSUPP); 1935} 1936 1937static int shmem_xattr_security_set(struct inode *inode, const char *name, 1938 const void *value, size_t size, int flags) 1939{ 1940 if (strcmp(name, "") == 0) 1941 return -EINVAL; 1942 return security_inode_setsecurity(inode, name, value, size, flags); 1943} 1944 1945struct xattr_handler shmem_xattr_security_handler = { 1946 .prefix = XATTR_SECURITY_PREFIX, 1947 .list = shmem_xattr_security_list, 1948 .get = shmem_xattr_security_get, 1949 .set = shmem_xattr_security_set, 1950}; 1951 1952static struct xattr_handler *shmem_xattr_handlers[] = { 1953 &shmem_xattr_acl_access_handler, 1954 &shmem_xattr_acl_default_handler, 1955 &shmem_xattr_security_handler, 1956 NULL 1957}; 1958#endif 1959 1960static struct dentry *shmem_get_parent(struct dentry *child) 1961{ 1962 return ERR_PTR(-ESTALE); 1963} 1964 1965static int shmem_match(struct inode *ino, void *vfh) 1966{ 1967 __u32 *fh = vfh; 1968 __u64 inum = fh[2]; 1969 inum = (inum << 32) | fh[1]; 1970 return ino->i_ino == inum && fh[0] == ino->i_generation; 1971} 1972 1973static struct dentry *shmem_get_dentry(struct super_block *sb, void *vfh) 1974{ 1975 struct dentry *de = NULL; 1976 struct inode *inode; 1977 __u32 *fh = vfh; 1978 __u64 inum = fh[2]; 1979 inum = (inum << 32) | fh[1]; 1980 1981 inode = ilookup5(sb, (unsigned long)(inum+fh[0]), shmem_match, vfh); 1982 if (inode) { 1983 de = d_find_alias(inode); 1984 iput(inode); 1985 } 1986 1987 return de? de: ERR_PTR(-ESTALE); 1988} 1989 1990static struct dentry *shmem_decode_fh(struct super_block *sb, __u32 *fh, 1991 int len, int type, 1992 int (*acceptable)(void *context, struct dentry *de), 1993 void *context) 1994{ 1995 if (len < 3) 1996 return ERR_PTR(-ESTALE); 1997 1998 return sb->s_export_op->find_exported_dentry(sb, fh, NULL, acceptable, 1999 context); 2000} 2001 2002static int shmem_encode_fh(struct dentry *dentry, __u32 *fh, int *len, 2003 int connectable) 2004{ 2005 struct inode *inode = dentry->d_inode; 2006 2007 if (*len < 3) 2008 return 255; 2009 2010 if (hlist_unhashed(&inode->i_hash)) { 2011 /* Unfortunately insert_inode_hash is not idempotent, 2012 * so as we hash inodes here rather than at creation 2013 * time, we need a lock to ensure we only try 2014 * to do it once 2015 */ 2016 static DEFINE_SPINLOCK(lock); 2017 spin_lock(&lock); 2018 if (hlist_unhashed(&inode->i_hash)) 2019 __insert_inode_hash(inode, 2020 inode->i_ino + inode->i_generation); 2021 spin_unlock(&lock); 2022 } 2023 2024 fh[0] = inode->i_generation; 2025 fh[1] = inode->i_ino; 2026 fh[2] = ((__u64)inode->i_ino) >> 32; 2027 2028 *len = 3; 2029 return 1; 2030} 2031 2032static struct export_operations shmem_export_ops = { 2033 .get_parent = shmem_get_parent, 2034 .get_dentry = shmem_get_dentry, 2035 .encode_fh = shmem_encode_fh, 2036 .decode_fh = shmem_decode_fh, 2037}; 2038 2039static int shmem_parse_options(char *options, int *mode, uid_t *uid, 2040 gid_t *gid, unsigned long *blocks, unsigned long *inodes, 2041 int *policy, nodemask_t *policy_nodes) 2042{ 2043 char *this_char, *value, *rest; 2044 2045 while (options != NULL) { 2046 this_char = options; 2047 for (;;) { 2048 /* 2049 * NUL-terminate this option: unfortunately, 2050 * mount options form a comma-separated list, 2051 * but mpol's nodelist may also contain commas. 2052 */ 2053 options = strchr(options, ','); 2054 if (options == NULL) 2055 break; 2056 options++; 2057 if (!isdigit(*options)) { 2058 options[-1] = '\0'; 2059 break; 2060 } 2061 } 2062 if (!*this_char) 2063 continue; 2064 if ((value = strchr(this_char,'=')) != NULL) { 2065 *value++ = 0; 2066 } else { 2067 printk(KERN_ERR 2068 "tmpfs: No value for mount option '%s'\n", 2069 this_char); 2070 return 1; 2071 } 2072 2073 if (!strcmp(this_char,"size")) { 2074 unsigned long long size; 2075 size = memparse(value,&rest); 2076 if (*rest == '%') { 2077 size <<= PAGE_SHIFT; 2078 size *= totalram_pages; 2079 do_div(size, 100); 2080 rest++; 2081 } 2082 if (*rest) 2083 goto bad_val; 2084 *blocks = size >> PAGE_CACHE_SHIFT; 2085 } else if (!strcmp(this_char,"nr_blocks")) { 2086 *blocks = memparse(value,&rest); 2087 if (*rest) 2088 goto bad_val; 2089 } else if (!strcmp(this_char,"nr_inodes")) { 2090 *inodes = memparse(value,&rest); 2091 if (*rest) 2092 goto bad_val; 2093 } else if (!strcmp(this_char,"mode")) { 2094 if (!mode) 2095 continue; 2096 *mode = simple_strtoul(value,&rest,8); 2097 if (*rest) 2098 goto bad_val; 2099 } else if (!strcmp(this_char,"uid")) { 2100 if (!uid) 2101 continue; 2102 *uid = simple_strtoul(value,&rest,0); 2103 if (*rest) 2104 goto bad_val; 2105 } else if (!strcmp(this_char,"gid")) { 2106 if (!gid) 2107 continue; 2108 *gid = simple_strtoul(value,&rest,0); 2109 if (*rest) 2110 goto bad_val; 2111 } else if (!strcmp(this_char,"mpol")) { 2112 if (shmem_parse_mpol(value,policy,policy_nodes)) 2113 goto bad_val; 2114 } else { 2115 printk(KERN_ERR "tmpfs: Bad mount option %s\n", 2116 this_char); 2117 return 1; 2118 } 2119 } 2120 return 0; 2121 2122bad_val: 2123 printk(KERN_ERR "tmpfs: Bad value '%s' for mount option '%s'\n", 2124 value, this_char); 2125 return 1; 2126 2127} 2128 2129static int shmem_remount_fs(struct super_block *sb, int *flags, char *data) 2130{ 2131 struct shmem_sb_info *sbinfo = SHMEM_SB(sb); 2132 unsigned long max_blocks = sbinfo->max_blocks; 2133 unsigned long max_inodes = sbinfo->max_inodes; 2134 int policy = sbinfo->policy; 2135 nodemask_t policy_nodes = sbinfo->policy_nodes; 2136 unsigned long blocks; 2137 unsigned long inodes; 2138 int error = -EINVAL; 2139 2140 if (shmem_parse_options(data, NULL, NULL, NULL, &max_blocks, 2141 &max_inodes, &policy, &policy_nodes)) 2142 return error; 2143 2144 spin_lock(&sbinfo->stat_lock); 2145 blocks = sbinfo->max_blocks - sbinfo->free_blocks; 2146 inodes = sbinfo->max_inodes - sbinfo->free_inodes; 2147 if (max_blocks < blocks) 2148 goto out; 2149 if (max_inodes < inodes) 2150 goto out; 2151 /* 2152 * Those tests also disallow limited->unlimited while any are in 2153 * use, so i_blocks will always be zero when max_blocks is zero; 2154 * but we must separately disallow unlimited->limited, because 2155 * in that case we have no record of how much is already in use. 2156 */ 2157 if (max_blocks && !sbinfo->max_blocks) 2158 goto out; 2159 if (max_inodes && !sbinfo->max_inodes) 2160 goto out; 2161 2162 error = 0; 2163 sbinfo->max_blocks = max_blocks; 2164 sbinfo->free_blocks = max_blocks - blocks; 2165 sbinfo->max_inodes = max_inodes; 2166 sbinfo->free_inodes = max_inodes - inodes; 2167 sbinfo->policy = policy; 2168 sbinfo->policy_nodes = policy_nodes; 2169out: 2170 spin_unlock(&sbinfo->stat_lock); 2171 return error; 2172} 2173#endif 2174 2175static void shmem_put_super(struct super_block *sb) 2176{ 2177 kfree(sb->s_fs_info); 2178 sb->s_fs_info = NULL; 2179} 2180 2181static int shmem_fill_super(struct super_block *sb, 2182 void *data, int silent) 2183{ 2184 struct inode *inode; 2185 struct dentry *root; 2186 int mode = S_IRWXUGO | S_ISVTX; 2187 uid_t uid = current->fsuid; 2188 gid_t gid = current->fsgid; 2189 int err = -ENOMEM; 2190 struct shmem_sb_info *sbinfo; 2191 unsigned long blocks = 0; 2192 unsigned long inodes = 0; 2193 int policy = MPOL_DEFAULT; 2194 nodemask_t policy_nodes = node_online_map; 2195 2196#ifdef CONFIG_TMPFS 2197 /* 2198 * Per default we only allow half of the physical ram per 2199 * tmpfs instance, limiting inodes to one per page of lowmem; 2200 * but the internal instance is left unlimited. 2201 */ 2202 if (!(sb->s_flags & MS_NOUSER)) { 2203 blocks = totalram_pages / 2; 2204 inodes = totalram_pages - totalhigh_pages; 2205 if (inodes > blocks) 2206 inodes = blocks; 2207 if (shmem_parse_options(data, &mode, &uid, &gid, &blocks, 2208 &inodes, &policy, &policy_nodes)) 2209 return -EINVAL; 2210 } 2211 sb->s_export_op = &shmem_export_ops; 2212#else 2213 sb->s_flags |= MS_NOUSER; 2214#endif 2215 2216 /* Round up to L1_CACHE_BYTES to resist false sharing */ 2217 sbinfo = kmalloc(max((int)sizeof(struct shmem_sb_info), 2218 L1_CACHE_BYTES), GFP_KERNEL); 2219 if (!sbinfo) 2220 return -ENOMEM; 2221 2222 spin_lock_init(&sbinfo->stat_lock); 2223 sbinfo->max_blocks = blocks; 2224 sbinfo->free_blocks = blocks; 2225 sbinfo->max_inodes = inodes; 2226 sbinfo->free_inodes = inodes; 2227 sbinfo->policy = policy; 2228 sbinfo->policy_nodes = policy_nodes; 2229 2230 sb->s_fs_info = sbinfo; 2231 sb->s_maxbytes = SHMEM_MAX_BYTES; 2232 sb->s_blocksize = PAGE_CACHE_SIZE; 2233 sb->s_blocksize_bits = PAGE_CACHE_SHIFT; 2234 sb->s_magic = TMPFS_MAGIC; 2235 sb->s_op = &shmem_ops; 2236 sb->s_time_gran = 1; 2237#ifdef CONFIG_TMPFS_POSIX_ACL 2238 sb->s_xattr = shmem_xattr_handlers; 2239 sb->s_flags |= MS_POSIXACL; 2240#endif 2241 2242 inode = shmem_get_inode(sb, S_IFDIR | mode, 0); 2243 if (!inode) 2244 goto failed; 2245 inode->i_uid = uid; 2246 inode->i_gid = gid; 2247 root = d_alloc_root(inode); 2248 if (!root) 2249 goto failed_iput; 2250 sb->s_root = root; 2251 return 0; 2252 2253failed_iput: 2254 iput(inode); 2255failed: 2256 shmem_put_super(sb); 2257 return err; 2258} 2259 2260static struct kmem_cache *shmem_inode_cachep; 2261 2262static struct inode *shmem_alloc_inode(struct super_block *sb) 2263{ 2264 struct shmem_inode_info *p; 2265 p = (struct shmem_inode_info *)kmem_cache_alloc(shmem_inode_cachep, SLAB_KERNEL); 2266 if (!p) 2267 return NULL; 2268 return &p->vfs_inode; 2269} 2270 2271static void shmem_destroy_inode(struct inode *inode) 2272{ 2273 if ((inode->i_mode & S_IFMT) == S_IFREG) { 2274 /* only struct inode is valid if it's an inline symlink */ 2275 mpol_free_shared_policy(&SHMEM_I(inode)->policy); 2276 } 2277 shmem_acl_destroy_inode(inode); 2278 kmem_cache_free(shmem_inode_cachep, SHMEM_I(inode)); 2279} 2280 2281static void init_once(void *foo, struct kmem_cache *cachep, 2282 unsigned long flags) 2283{ 2284 struct shmem_inode_info *p = (struct shmem_inode_info *) foo; 2285 2286 if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) == 2287 SLAB_CTOR_CONSTRUCTOR) { 2288 inode_init_once(&p->vfs_inode); 2289#ifdef CONFIG_TMPFS_POSIX_ACL 2290 p->i_acl = NULL; 2291 p->i_default_acl = NULL; 2292#endif 2293 } 2294} 2295 2296static int init_inodecache(void) 2297{ 2298 shmem_inode_cachep = kmem_cache_create("shmem_inode_cache", 2299 sizeof(struct shmem_inode_info), 2300 0, 0, init_once, NULL); 2301 if (shmem_inode_cachep == NULL) 2302 return -ENOMEM; 2303 return 0; 2304} 2305 2306static void destroy_inodecache(void) 2307{ 2308 kmem_cache_destroy(shmem_inode_cachep); 2309} 2310 2311static const struct address_space_operations shmem_aops = { 2312 .writepage = shmem_writepage, 2313 .set_page_dirty = __set_page_dirty_nobuffers, 2314#ifdef CONFIG_TMPFS 2315 .prepare_write = shmem_prepare_write, 2316 .commit_write = simple_commit_write, 2317#endif 2318 .migratepage = migrate_page, 2319}; 2320 2321static struct file_operations shmem_file_operations = { 2322 .mmap = shmem_mmap, 2323#ifdef CONFIG_TMPFS 2324 .llseek = generic_file_llseek, 2325 .read = shmem_file_read, 2326 .write = shmem_file_write, 2327 .fsync = simple_sync_file, 2328 .sendfile = shmem_file_sendfile, 2329#endif 2330}; 2331 2332static struct inode_operations shmem_inode_operations = { 2333 .truncate = shmem_truncate, 2334 .setattr = shmem_notify_change, 2335 .truncate_range = shmem_truncate_range, 2336#ifdef CONFIG_TMPFS_POSIX_ACL 2337 .setxattr = generic_setxattr, 2338 .getxattr = generic_getxattr, 2339 .listxattr = generic_listxattr, 2340 .removexattr = generic_removexattr, 2341 .permission = shmem_permission, 2342#endif 2343 2344}; 2345 2346static struct inode_operations shmem_dir_inode_operations = { 2347#ifdef CONFIG_TMPFS 2348 .create = shmem_create, 2349 .lookup = simple_lookup, 2350 .link = shmem_link, 2351 .unlink = shmem_unlink, 2352 .symlink = shmem_symlink, 2353 .mkdir = shmem_mkdir, 2354 .rmdir = shmem_rmdir, 2355 .mknod = shmem_mknod, 2356 .rename = shmem_rename, 2357#endif 2358#ifdef CONFIG_TMPFS_POSIX_ACL 2359 .setattr = shmem_notify_change, 2360 .setxattr = generic_setxattr, 2361 .getxattr = generic_getxattr, 2362 .listxattr = generic_listxattr, 2363 .removexattr = generic_removexattr, 2364 .permission = shmem_permission, 2365#endif 2366}; 2367 2368static struct inode_operations shmem_special_inode_operations = { 2369#ifdef CONFIG_TMPFS_POSIX_ACL 2370 .setattr = shmem_notify_change, 2371 .setxattr = generic_setxattr, 2372 .getxattr = generic_getxattr, 2373 .listxattr = generic_listxattr, 2374 .removexattr = generic_removexattr, 2375 .permission = shmem_permission, 2376#endif 2377}; 2378 2379static struct super_operations shmem_ops = { 2380 .alloc_inode = shmem_alloc_inode, 2381 .destroy_inode = shmem_destroy_inode, 2382#ifdef CONFIG_TMPFS 2383 .statfs = shmem_statfs, 2384 .remount_fs = shmem_remount_fs, 2385#endif 2386 .delete_inode = shmem_delete_inode, 2387 .drop_inode = generic_delete_inode, 2388 .put_super = shmem_put_super, 2389}; 2390 2391static struct vm_operations_struct shmem_vm_ops = { 2392 .nopage = shmem_nopage, 2393 .populate = shmem_populate, 2394#ifdef CONFIG_NUMA 2395 .set_policy = shmem_set_policy, 2396 .get_policy = shmem_get_policy, 2397#endif 2398}; 2399 2400 2401static int shmem_get_sb(struct file_system_type *fs_type, 2402 int flags, const char *dev_name, void *data, struct vfsmount *mnt) 2403{ 2404 return get_sb_nodev(fs_type, flags, data, shmem_fill_super, mnt); 2405} 2406 2407static struct file_system_type tmpfs_fs_type = { 2408 .owner = THIS_MODULE, 2409 .name = "tmpfs", 2410 .get_sb = shmem_get_sb, 2411 .kill_sb = kill_litter_super, 2412}; 2413static struct vfsmount *shm_mnt; 2414 2415static int __init init_tmpfs(void) 2416{ 2417 int error; 2418 2419 error = init_inodecache(); 2420 if (error) 2421 goto out3; 2422 2423 error = register_filesystem(&tmpfs_fs_type); 2424 if (error) { 2425 printk(KERN_ERR "Could not register tmpfs\n"); 2426 goto out2; 2427 } 2428 2429 shm_mnt = vfs_kern_mount(&tmpfs_fs_type, MS_NOUSER, 2430 tmpfs_fs_type.name, NULL); 2431 if (IS_ERR(shm_mnt)) { 2432 error = PTR_ERR(shm_mnt); 2433 printk(KERN_ERR "Could not kern_mount tmpfs\n"); 2434 goto out1; 2435 } 2436 return 0; 2437 2438out1: 2439 unregister_filesystem(&tmpfs_fs_type); 2440out2: 2441 destroy_inodecache(); 2442out3: 2443 shm_mnt = ERR_PTR(error); 2444 return error; 2445} 2446module_init(init_tmpfs) 2447 2448/* 2449 * shmem_file_setup - get an unlinked file living in tmpfs 2450 * 2451 * @name: name for dentry (to be seen in /proc/<pid>/maps 2452 * @size: size to be set for the file 2453 * 2454 */ 2455struct file *shmem_file_setup(char *name, loff_t size, unsigned long flags) 2456{ 2457 int error; 2458 struct file *file; 2459 struct inode *inode; 2460 struct dentry *dentry, *root; 2461 struct qstr this; 2462 2463 if (IS_ERR(shm_mnt)) 2464 return (void *)shm_mnt; 2465 2466 if (size < 0 || size > SHMEM_MAX_BYTES) 2467 return ERR_PTR(-EINVAL); 2468 2469 if (shmem_acct_size(flags, size)) 2470 return ERR_PTR(-ENOMEM); 2471 2472 error = -ENOMEM; 2473 this.name = name; 2474 this.len = strlen(name); 2475 this.hash = 0; /* will go */ 2476 root = shm_mnt->mnt_root; 2477 dentry = d_alloc(root, &this); 2478 if (!dentry) 2479 goto put_memory; 2480 2481 error = -ENFILE; 2482 file = get_empty_filp(); 2483 if (!file) 2484 goto put_dentry; 2485 2486 error = -ENOSPC; 2487 inode = shmem_get_inode(root->d_sb, S_IFREG | S_IRWXUGO, 0); 2488 if (!inode) 2489 goto close_file; 2490 2491 SHMEM_I(inode)->flags = flags & VM_ACCOUNT; 2492 d_instantiate(dentry, inode); 2493 inode->i_size = size; 2494 inode->i_nlink = 0; /* It is unlinked */ 2495 file->f_vfsmnt = mntget(shm_mnt); 2496 file->f_dentry = dentry; 2497 file->f_mapping = inode->i_mapping; 2498 file->f_op = &shmem_file_operations; 2499 file->f_mode = FMODE_WRITE | FMODE_READ; 2500 return file; 2501 2502close_file: 2503 put_filp(file); 2504put_dentry: 2505 dput(dentry); 2506put_memory: 2507 shmem_unacct_size(flags, size); 2508 return ERR_PTR(error); 2509} 2510 2511/* 2512 * shmem_zero_setup - setup a shared anonymous mapping 2513 * 2514 * @vma: the vma to be mmapped is prepared by do_mmap_pgoff 2515 */ 2516int shmem_zero_setup(struct vm_area_struct *vma) 2517{ 2518 struct file *file; 2519 loff_t size = vma->vm_end - vma->vm_start; 2520 2521 file = shmem_file_setup("dev/zero", size, vma->vm_flags); 2522 if (IS_ERR(file)) 2523 return PTR_ERR(file); 2524 2525 if (vma->vm_file) 2526 fput(vma->vm_file); 2527 vma->vm_file = file; 2528 vma->vm_ops = &shmem_vm_ops; 2529 return 0; 2530} 2531