| 1 | /* |
| 2 | * mm/truncate.c - code for taking down pages from address_spaces |
| 3 | * |
| 4 | * Copyright (C) 2002, Linus Torvalds |
| 5 | * |
| 6 | * 10Sep2002 Andrew Morton |
| 7 | * Initial version. |
| 8 | */ |
| 9 | |
| 10 | #include <linux/kernel.h> |
| 11 | #include <linux/backing-dev.h> |
| 12 | #include <linux/gfp.h> |
| 13 | #include <linux/mm.h> |
| 14 | #include <linux/swap.h> |
| 15 | #include <linux/export.h> |
| 16 | #include <linux/pagemap.h> |
| 17 | #include <linux/highmem.h> |
| 18 | #include <linux/pagevec.h> |
| 19 | #include <linux/task_io_accounting_ops.h> |
| 20 | #include <linux/buffer_head.h> /* grr. try_to_release_page, |
| 21 | do_invalidatepage */ |
| 22 | #include <linux/cleancache.h> |
| 23 | #include "internal.h" |
| 24 | |
| 25 | static void clear_exceptional_entry(struct address_space *mapping, |
| 26 | pgoff_t index, void *entry) |
| 27 | { |
| 28 | struct radix_tree_node *node; |
| 29 | void **slot; |
| 30 | |
| 31 | /* Handled by shmem itself */ |
| 32 | if (shmem_mapping(mapping)) |
| 33 | return; |
| 34 | |
| 35 | spin_lock_irq(&mapping->tree_lock); |
| 36 | /* |
| 37 | * Regular page slots are stabilized by the page lock even |
| 38 | * without the tree itself locked. These unlocked entries |
| 39 | * need verification under the tree lock. |
| 40 | */ |
| 41 | if (!__radix_tree_lookup(&mapping->page_tree, index, &node, &slot)) |
| 42 | goto unlock; |
| 43 | if (*slot != entry) |
| 44 | goto unlock; |
| 45 | radix_tree_replace_slot(slot, NULL); |
| 46 | mapping->nrshadows--; |
| 47 | if (!node) |
| 48 | goto unlock; |
| 49 | workingset_node_shadows_dec(node); |
| 50 | /* |
| 51 | * Don't track node without shadow entries. |
| 52 | * |
| 53 | * Avoid acquiring the list_lru lock if already untracked. |
| 54 | * The list_empty() test is safe as node->private_list is |
| 55 | * protected by mapping->tree_lock. |
| 56 | */ |
| 57 | if (!workingset_node_shadows(node) && |
| 58 | !list_empty(&node->private_list)) |
| 59 | list_lru_del(&workingset_shadow_nodes, &node->private_list); |
| 60 | __radix_tree_delete_node(&mapping->page_tree, node); |
| 61 | unlock: |
| 62 | spin_unlock_irq(&mapping->tree_lock); |
| 63 | } |
| 64 | |
| 65 | /** |
| 66 | * do_invalidatepage - invalidate part or all of a page |
| 67 | * @page: the page which is affected |
| 68 | * @offset: start of the range to invalidate |
| 69 | * @length: length of the range to invalidate |
| 70 | * |
| 71 | * do_invalidatepage() is called when all or part of the page has become |
| 72 | * invalidated by a truncate operation. |
| 73 | * |
| 74 | * do_invalidatepage() does not have to release all buffers, but it must |
| 75 | * ensure that no dirty buffer is left outside @offset and that no I/O |
| 76 | * is underway against any of the blocks which are outside the truncation |
| 77 | * point. Because the caller is about to free (and possibly reuse) those |
| 78 | * blocks on-disk. |
| 79 | */ |
| 80 | void do_invalidatepage(struct page *page, unsigned int offset, |
| 81 | unsigned int length) |
| 82 | { |
| 83 | void (*invalidatepage)(struct page *, unsigned int, unsigned int); |
| 84 | |
| 85 | invalidatepage = page->mapping->a_ops->invalidatepage; |
| 86 | #ifdef CONFIG_BLOCK |
| 87 | if (!invalidatepage) |
| 88 | invalidatepage = block_invalidatepage; |
| 89 | #endif |
| 90 | if (invalidatepage) |
| 91 | (*invalidatepage)(page, offset, length); |
| 92 | } |
| 93 | |
| 94 | /* |
| 95 | * This cancels just the dirty bit on the kernel page itself, it |
| 96 | * does NOT actually remove dirty bits on any mmap's that may be |
| 97 | * around. It also leaves the page tagged dirty, so any sync |
| 98 | * activity will still find it on the dirty lists, and in particular, |
| 99 | * clear_page_dirty_for_io() will still look at the dirty bits in |
| 100 | * the VM. |
| 101 | * |
| 102 | * Doing this should *normally* only ever be done when a page |
| 103 | * is truncated, and is not actually mapped anywhere at all. However, |
| 104 | * fs/buffer.c does this when it notices that somebody has cleaned |
| 105 | * out all the buffers on a page without actually doing it through |
| 106 | * the VM. Can you say "ext3 is horribly ugly"? Tought you could. |
| 107 | */ |
| 108 | void cancel_dirty_page(struct page *page, unsigned int account_size) |
| 109 | { |
| 110 | if (TestClearPageDirty(page)) { |
| 111 | struct address_space *mapping = page->mapping; |
| 112 | if (mapping && mapping_cap_account_dirty(mapping)) { |
| 113 | dec_zone_page_state(page, NR_FILE_DIRTY); |
| 114 | dec_bdi_stat(mapping->backing_dev_info, |
| 115 | BDI_RECLAIMABLE); |
| 116 | if (account_size) |
| 117 | task_io_account_cancelled_write(account_size); |
| 118 | } |
| 119 | } |
| 120 | } |
| 121 | EXPORT_SYMBOL(cancel_dirty_page); |
| 122 | |
| 123 | /* |
| 124 | * If truncate cannot remove the fs-private metadata from the page, the page |
| 125 | * becomes orphaned. It will be left on the LRU and may even be mapped into |
| 126 | * user pagetables if we're racing with filemap_fault(). |
| 127 | * |
| 128 | * We need to bale out if page->mapping is no longer equal to the original |
| 129 | * mapping. This happens a) when the VM reclaimed the page while we waited on |
| 130 | * its lock, b) when a concurrent invalidate_mapping_pages got there first and |
| 131 | * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space. |
| 132 | */ |
| 133 | static int |
| 134 | truncate_complete_page(struct address_space *mapping, struct page *page) |
| 135 | { |
| 136 | if (page->mapping != mapping) |
| 137 | return -EIO; |
| 138 | |
| 139 | if (page_has_private(page)) |
| 140 | do_invalidatepage(page, 0, PAGE_CACHE_SIZE); |
| 141 | |
| 142 | cancel_dirty_page(page, PAGE_CACHE_SIZE); |
| 143 | |
| 144 | ClearPageMappedToDisk(page); |
| 145 | delete_from_page_cache(page); |
| 146 | return 0; |
| 147 | } |
| 148 | |
| 149 | /* |
| 150 | * This is for invalidate_mapping_pages(). That function can be called at |
| 151 | * any time, and is not supposed to throw away dirty pages. But pages can |
| 152 | * be marked dirty at any time too, so use remove_mapping which safely |
| 153 | * discards clean, unused pages. |
| 154 | * |
| 155 | * Returns non-zero if the page was successfully invalidated. |
| 156 | */ |
| 157 | static int |
| 158 | invalidate_complete_page(struct address_space *mapping, struct page *page) |
| 159 | { |
| 160 | int ret; |
| 161 | |
| 162 | if (page->mapping != mapping) |
| 163 | return 0; |
| 164 | |
| 165 | if (page_has_private(page) && !try_to_release_page(page, 0)) |
| 166 | return 0; |
| 167 | |
| 168 | ret = remove_mapping(mapping, page); |
| 169 | |
| 170 | return ret; |
| 171 | } |
| 172 | |
| 173 | int truncate_inode_page(struct address_space *mapping, struct page *page) |
| 174 | { |
| 175 | if (page_mapped(page)) { |
| 176 | unmap_mapping_range(mapping, |
| 177 | (loff_t)page->index << PAGE_CACHE_SHIFT, |
| 178 | PAGE_CACHE_SIZE, 0); |
| 179 | } |
| 180 | return truncate_complete_page(mapping, page); |
| 181 | } |
| 182 | |
| 183 | /* |
| 184 | * Used to get rid of pages on hardware memory corruption. |
| 185 | */ |
| 186 | int generic_error_remove_page(struct address_space *mapping, struct page *page) |
| 187 | { |
| 188 | if (!mapping) |
| 189 | return -EINVAL; |
| 190 | /* |
| 191 | * Only punch for normal data pages for now. |
| 192 | * Handling other types like directories would need more auditing. |
| 193 | */ |
| 194 | if (!S_ISREG(mapping->host->i_mode)) |
| 195 | return -EIO; |
| 196 | return truncate_inode_page(mapping, page); |
| 197 | } |
| 198 | EXPORT_SYMBOL(generic_error_remove_page); |
| 199 | |
| 200 | /* |
| 201 | * Safely invalidate one page from its pagecache mapping. |
| 202 | * It only drops clean, unused pages. The page must be locked. |
| 203 | * |
| 204 | * Returns 1 if the page is successfully invalidated, otherwise 0. |
| 205 | */ |
| 206 | int invalidate_inode_page(struct page *page) |
| 207 | { |
| 208 | struct address_space *mapping = page_mapping(page); |
| 209 | if (!mapping) |
| 210 | return 0; |
| 211 | if (PageDirty(page) || PageWriteback(page)) |
| 212 | return 0; |
| 213 | if (page_mapped(page)) |
| 214 | return 0; |
| 215 | return invalidate_complete_page(mapping, page); |
| 216 | } |
| 217 | |
| 218 | /** |
| 219 | * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets |
| 220 | * @mapping: mapping to truncate |
| 221 | * @lstart: offset from which to truncate |
| 222 | * @lend: offset to which to truncate (inclusive) |
| 223 | * |
| 224 | * Truncate the page cache, removing the pages that are between |
| 225 | * specified offsets (and zeroing out partial pages |
| 226 | * if lstart or lend + 1 is not page aligned). |
| 227 | * |
| 228 | * Truncate takes two passes - the first pass is nonblocking. It will not |
| 229 | * block on page locks and it will not block on writeback. The second pass |
| 230 | * will wait. This is to prevent as much IO as possible in the affected region. |
| 231 | * The first pass will remove most pages, so the search cost of the second pass |
| 232 | * is low. |
| 233 | * |
| 234 | * We pass down the cache-hot hint to the page freeing code. Even if the |
| 235 | * mapping is large, it is probably the case that the final pages are the most |
| 236 | * recently touched, and freeing happens in ascending file offset order. |
| 237 | * |
| 238 | * Note that since ->invalidatepage() accepts range to invalidate |
| 239 | * truncate_inode_pages_range is able to handle cases where lend + 1 is not |
| 240 | * page aligned properly. |
| 241 | */ |
| 242 | void truncate_inode_pages_range(struct address_space *mapping, |
| 243 | loff_t lstart, loff_t lend) |
| 244 | { |
| 245 | pgoff_t start; /* inclusive */ |
| 246 | pgoff_t end; /* exclusive */ |
| 247 | unsigned int partial_start; /* inclusive */ |
| 248 | unsigned int partial_end; /* exclusive */ |
| 249 | struct pagevec pvec; |
| 250 | pgoff_t indices[PAGEVEC_SIZE]; |
| 251 | pgoff_t index; |
| 252 | int i; |
| 253 | |
| 254 | cleancache_invalidate_inode(mapping); |
| 255 | if (mapping->nrpages == 0 && mapping->nrshadows == 0) |
| 256 | return; |
| 257 | |
| 258 | /* Offsets within partial pages */ |
| 259 | partial_start = lstart & (PAGE_CACHE_SIZE - 1); |
| 260 | partial_end = (lend + 1) & (PAGE_CACHE_SIZE - 1); |
| 261 | |
| 262 | /* |
| 263 | * 'start' and 'end' always covers the range of pages to be fully |
| 264 | * truncated. Partial pages are covered with 'partial_start' at the |
| 265 | * start of the range and 'partial_end' at the end of the range. |
| 266 | * Note that 'end' is exclusive while 'lend' is inclusive. |
| 267 | */ |
| 268 | start = (lstart + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT; |
| 269 | if (lend == -1) |
| 270 | /* |
| 271 | * lend == -1 indicates end-of-file so we have to set 'end' |
| 272 | * to the highest possible pgoff_t and since the type is |
| 273 | * unsigned we're using -1. |
| 274 | */ |
| 275 | end = -1; |
| 276 | else |
| 277 | end = (lend + 1) >> PAGE_CACHE_SHIFT; |
| 278 | |
| 279 | pagevec_init(&pvec, 0); |
| 280 | index = start; |
| 281 | while (index < end && pagevec_lookup_entries(&pvec, mapping, index, |
| 282 | min(end - index, (pgoff_t)PAGEVEC_SIZE), |
| 283 | indices)) { |
| 284 | mem_cgroup_uncharge_start(); |
| 285 | for (i = 0; i < pagevec_count(&pvec); i++) { |
| 286 | struct page *page = pvec.pages[i]; |
| 287 | |
| 288 | /* We rely upon deletion not changing page->index */ |
| 289 | index = indices[i]; |
| 290 | if (index >= end) |
| 291 | break; |
| 292 | |
| 293 | if (radix_tree_exceptional_entry(page)) { |
| 294 | clear_exceptional_entry(mapping, index, page); |
| 295 | continue; |
| 296 | } |
| 297 | |
| 298 | if (!trylock_page(page)) |
| 299 | continue; |
| 300 | WARN_ON(page->index != index); |
| 301 | if (PageWriteback(page)) { |
| 302 | unlock_page(page); |
| 303 | continue; |
| 304 | } |
| 305 | truncate_inode_page(mapping, page); |
| 306 | unlock_page(page); |
| 307 | } |
| 308 | pagevec_remove_exceptionals(&pvec); |
| 309 | pagevec_release(&pvec); |
| 310 | mem_cgroup_uncharge_end(); |
| 311 | cond_resched(); |
| 312 | index++; |
| 313 | } |
| 314 | |
| 315 | if (partial_start) { |
| 316 | struct page *page = find_lock_page(mapping, start - 1); |
| 317 | if (page) { |
| 318 | unsigned int top = PAGE_CACHE_SIZE; |
| 319 | if (start > end) { |
| 320 | /* Truncation within a single page */ |
| 321 | top = partial_end; |
| 322 | partial_end = 0; |
| 323 | } |
| 324 | wait_on_page_writeback(page); |
| 325 | zero_user_segment(page, partial_start, top); |
| 326 | cleancache_invalidate_page(mapping, page); |
| 327 | if (page_has_private(page)) |
| 328 | do_invalidatepage(page, partial_start, |
| 329 | top - partial_start); |
| 330 | unlock_page(page); |
| 331 | page_cache_release(page); |
| 332 | } |
| 333 | } |
| 334 | if (partial_end) { |
| 335 | struct page *page = find_lock_page(mapping, end); |
| 336 | if (page) { |
| 337 | wait_on_page_writeback(page); |
| 338 | zero_user_segment(page, 0, partial_end); |
| 339 | cleancache_invalidate_page(mapping, page); |
| 340 | if (page_has_private(page)) |
| 341 | do_invalidatepage(page, 0, |
| 342 | partial_end); |
| 343 | unlock_page(page); |
| 344 | page_cache_release(page); |
| 345 | } |
| 346 | } |
| 347 | /* |
| 348 | * If the truncation happened within a single page no pages |
| 349 | * will be released, just zeroed, so we can bail out now. |
| 350 | */ |
| 351 | if (start >= end) |
| 352 | return; |
| 353 | |
| 354 | index = start; |
| 355 | for ( ; ; ) { |
| 356 | cond_resched(); |
| 357 | if (!pagevec_lookup_entries(&pvec, mapping, index, |
| 358 | min(end - index, (pgoff_t)PAGEVEC_SIZE), indices)) { |
| 359 | /* If all gone from start onwards, we're done */ |
| 360 | if (index == start) |
| 361 | break; |
| 362 | /* Otherwise restart to make sure all gone */ |
| 363 | index = start; |
| 364 | continue; |
| 365 | } |
| 366 | if (index == start && indices[0] >= end) { |
| 367 | /* All gone out of hole to be punched, we're done */ |
| 368 | pagevec_remove_exceptionals(&pvec); |
| 369 | pagevec_release(&pvec); |
| 370 | break; |
| 371 | } |
| 372 | mem_cgroup_uncharge_start(); |
| 373 | for (i = 0; i < pagevec_count(&pvec); i++) { |
| 374 | struct page *page = pvec.pages[i]; |
| 375 | |
| 376 | /* We rely upon deletion not changing page->index */ |
| 377 | index = indices[i]; |
| 378 | if (index >= end) { |
| 379 | /* Restart punch to make sure all gone */ |
| 380 | index = start - 1; |
| 381 | break; |
| 382 | } |
| 383 | |
| 384 | if (radix_tree_exceptional_entry(page)) { |
| 385 | clear_exceptional_entry(mapping, index, page); |
| 386 | continue; |
| 387 | } |
| 388 | |
| 389 | lock_page(page); |
| 390 | WARN_ON(page->index != index); |
| 391 | wait_on_page_writeback(page); |
| 392 | truncate_inode_page(mapping, page); |
| 393 | unlock_page(page); |
| 394 | } |
| 395 | pagevec_remove_exceptionals(&pvec); |
| 396 | pagevec_release(&pvec); |
| 397 | mem_cgroup_uncharge_end(); |
| 398 | index++; |
| 399 | } |
| 400 | cleancache_invalidate_inode(mapping); |
| 401 | } |
| 402 | EXPORT_SYMBOL(truncate_inode_pages_range); |
| 403 | |
| 404 | /** |
| 405 | * truncate_inode_pages - truncate *all* the pages from an offset |
| 406 | * @mapping: mapping to truncate |
| 407 | * @lstart: offset from which to truncate |
| 408 | * |
| 409 | * Called under (and serialised by) inode->i_mutex. |
| 410 | * |
| 411 | * Note: When this function returns, there can be a page in the process of |
| 412 | * deletion (inside __delete_from_page_cache()) in the specified range. Thus |
| 413 | * mapping->nrpages can be non-zero when this function returns even after |
| 414 | * truncation of the whole mapping. |
| 415 | */ |
| 416 | void truncate_inode_pages(struct address_space *mapping, loff_t lstart) |
| 417 | { |
| 418 | truncate_inode_pages_range(mapping, lstart, (loff_t)-1); |
| 419 | } |
| 420 | EXPORT_SYMBOL(truncate_inode_pages); |
| 421 | |
| 422 | /** |
| 423 | * truncate_inode_pages_final - truncate *all* pages before inode dies |
| 424 | * @mapping: mapping to truncate |
| 425 | * |
| 426 | * Called under (and serialized by) inode->i_mutex. |
| 427 | * |
| 428 | * Filesystems have to use this in the .evict_inode path to inform the |
| 429 | * VM that this is the final truncate and the inode is going away. |
| 430 | */ |
| 431 | void truncate_inode_pages_final(struct address_space *mapping) |
| 432 | { |
| 433 | unsigned long nrshadows; |
| 434 | unsigned long nrpages; |
| 435 | |
| 436 | /* |
| 437 | * Page reclaim can not participate in regular inode lifetime |
| 438 | * management (can't call iput()) and thus can race with the |
| 439 | * inode teardown. Tell it when the address space is exiting, |
| 440 | * so that it does not install eviction information after the |
| 441 | * final truncate has begun. |
| 442 | */ |
| 443 | mapping_set_exiting(mapping); |
| 444 | |
| 445 | /* |
| 446 | * When reclaim installs eviction entries, it increases |
| 447 | * nrshadows first, then decreases nrpages. Make sure we see |
| 448 | * this in the right order or we might miss an entry. |
| 449 | */ |
| 450 | nrpages = mapping->nrpages; |
| 451 | smp_rmb(); |
| 452 | nrshadows = mapping->nrshadows; |
| 453 | |
| 454 | if (nrpages || nrshadows) { |
| 455 | /* |
| 456 | * As truncation uses a lockless tree lookup, cycle |
| 457 | * the tree lock to make sure any ongoing tree |
| 458 | * modification that does not see AS_EXITING is |
| 459 | * completed before starting the final truncate. |
| 460 | */ |
| 461 | spin_lock_irq(&mapping->tree_lock); |
| 462 | spin_unlock_irq(&mapping->tree_lock); |
| 463 | |
| 464 | truncate_inode_pages(mapping, 0); |
| 465 | } |
| 466 | } |
| 467 | EXPORT_SYMBOL(truncate_inode_pages_final); |
| 468 | |
| 469 | /** |
| 470 | * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode |
| 471 | * @mapping: the address_space which holds the pages to invalidate |
| 472 | * @start: the offset 'from' which to invalidate |
| 473 | * @end: the offset 'to' which to invalidate (inclusive) |
| 474 | * |
| 475 | * This function only removes the unlocked pages, if you want to |
| 476 | * remove all the pages of one inode, you must call truncate_inode_pages. |
| 477 | * |
| 478 | * invalidate_mapping_pages() will not block on IO activity. It will not |
| 479 | * invalidate pages which are dirty, locked, under writeback or mapped into |
| 480 | * pagetables. |
| 481 | */ |
| 482 | unsigned long invalidate_mapping_pages(struct address_space *mapping, |
| 483 | pgoff_t start, pgoff_t end) |
| 484 | { |
| 485 | pgoff_t indices[PAGEVEC_SIZE]; |
| 486 | struct pagevec pvec; |
| 487 | pgoff_t index = start; |
| 488 | unsigned long ret; |
| 489 | unsigned long count = 0; |
| 490 | int i; |
| 491 | |
| 492 | pagevec_init(&pvec, 0); |
| 493 | while (index <= end && pagevec_lookup_entries(&pvec, mapping, index, |
| 494 | min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1, |
| 495 | indices)) { |
| 496 | mem_cgroup_uncharge_start(); |
| 497 | for (i = 0; i < pagevec_count(&pvec); i++) { |
| 498 | struct page *page = pvec.pages[i]; |
| 499 | |
| 500 | /* We rely upon deletion not changing page->index */ |
| 501 | index = indices[i]; |
| 502 | if (index > end) |
| 503 | break; |
| 504 | |
| 505 | if (radix_tree_exceptional_entry(page)) { |
| 506 | clear_exceptional_entry(mapping, index, page); |
| 507 | continue; |
| 508 | } |
| 509 | |
| 510 | if (!trylock_page(page)) |
| 511 | continue; |
| 512 | WARN_ON(page->index != index); |
| 513 | ret = invalidate_inode_page(page); |
| 514 | unlock_page(page); |
| 515 | /* |
| 516 | * Invalidation is a hint that the page is no longer |
| 517 | * of interest and try to speed up its reclaim. |
| 518 | */ |
| 519 | if (!ret) |
| 520 | deactivate_page(page); |
| 521 | count += ret; |
| 522 | } |
| 523 | pagevec_remove_exceptionals(&pvec); |
| 524 | pagevec_release(&pvec); |
| 525 | mem_cgroup_uncharge_end(); |
| 526 | cond_resched(); |
| 527 | index++; |
| 528 | } |
| 529 | return count; |
| 530 | } |
| 531 | EXPORT_SYMBOL(invalidate_mapping_pages); |
| 532 | |
| 533 | /* |
| 534 | * This is like invalidate_complete_page(), except it ignores the page's |
| 535 | * refcount. We do this because invalidate_inode_pages2() needs stronger |
| 536 | * invalidation guarantees, and cannot afford to leave pages behind because |
| 537 | * shrink_page_list() has a temp ref on them, or because they're transiently |
| 538 | * sitting in the lru_cache_add() pagevecs. |
| 539 | */ |
| 540 | static int |
| 541 | invalidate_complete_page2(struct address_space *mapping, struct page *page) |
| 542 | { |
| 543 | if (page->mapping != mapping) |
| 544 | return 0; |
| 545 | |
| 546 | if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL)) |
| 547 | return 0; |
| 548 | |
| 549 | spin_lock_irq(&mapping->tree_lock); |
| 550 | if (PageDirty(page)) |
| 551 | goto failed; |
| 552 | |
| 553 | BUG_ON(page_has_private(page)); |
| 554 | __delete_from_page_cache(page, NULL); |
| 555 | spin_unlock_irq(&mapping->tree_lock); |
| 556 | mem_cgroup_uncharge_cache_page(page); |
| 557 | |
| 558 | if (mapping->a_ops->freepage) |
| 559 | mapping->a_ops->freepage(page); |
| 560 | |
| 561 | page_cache_release(page); /* pagecache ref */ |
| 562 | return 1; |
| 563 | failed: |
| 564 | spin_unlock_irq(&mapping->tree_lock); |
| 565 | return 0; |
| 566 | } |
| 567 | |
| 568 | static int do_launder_page(struct address_space *mapping, struct page *page) |
| 569 | { |
| 570 | if (!PageDirty(page)) |
| 571 | return 0; |
| 572 | if (page->mapping != mapping || mapping->a_ops->launder_page == NULL) |
| 573 | return 0; |
| 574 | return mapping->a_ops->launder_page(page); |
| 575 | } |
| 576 | |
| 577 | /** |
| 578 | * invalidate_inode_pages2_range - remove range of pages from an address_space |
| 579 | * @mapping: the address_space |
| 580 | * @start: the page offset 'from' which to invalidate |
| 581 | * @end: the page offset 'to' which to invalidate (inclusive) |
| 582 | * |
| 583 | * Any pages which are found to be mapped into pagetables are unmapped prior to |
| 584 | * invalidation. |
| 585 | * |
| 586 | * Returns -EBUSY if any pages could not be invalidated. |
| 587 | */ |
| 588 | int invalidate_inode_pages2_range(struct address_space *mapping, |
| 589 | pgoff_t start, pgoff_t end) |
| 590 | { |
| 591 | pgoff_t indices[PAGEVEC_SIZE]; |
| 592 | struct pagevec pvec; |
| 593 | pgoff_t index; |
| 594 | int i; |
| 595 | int ret = 0; |
| 596 | int ret2 = 0; |
| 597 | int did_range_unmap = 0; |
| 598 | |
| 599 | cleancache_invalidate_inode(mapping); |
| 600 | pagevec_init(&pvec, 0); |
| 601 | index = start; |
| 602 | while (index <= end && pagevec_lookup_entries(&pvec, mapping, index, |
| 603 | min(end - index, (pgoff_t)PAGEVEC_SIZE - 1) + 1, |
| 604 | indices)) { |
| 605 | mem_cgroup_uncharge_start(); |
| 606 | for (i = 0; i < pagevec_count(&pvec); i++) { |
| 607 | struct page *page = pvec.pages[i]; |
| 608 | |
| 609 | /* We rely upon deletion not changing page->index */ |
| 610 | index = indices[i]; |
| 611 | if (index > end) |
| 612 | break; |
| 613 | |
| 614 | if (radix_tree_exceptional_entry(page)) { |
| 615 | clear_exceptional_entry(mapping, index, page); |
| 616 | continue; |
| 617 | } |
| 618 | |
| 619 | lock_page(page); |
| 620 | WARN_ON(page->index != index); |
| 621 | if (page->mapping != mapping) { |
| 622 | unlock_page(page); |
| 623 | continue; |
| 624 | } |
| 625 | wait_on_page_writeback(page); |
| 626 | if (page_mapped(page)) { |
| 627 | if (!did_range_unmap) { |
| 628 | /* |
| 629 | * Zap the rest of the file in one hit. |
| 630 | */ |
| 631 | unmap_mapping_range(mapping, |
| 632 | (loff_t)index << PAGE_CACHE_SHIFT, |
| 633 | (loff_t)(1 + end - index) |
| 634 | << PAGE_CACHE_SHIFT, |
| 635 | 0); |
| 636 | did_range_unmap = 1; |
| 637 | } else { |
| 638 | /* |
| 639 | * Just zap this page |
| 640 | */ |
| 641 | unmap_mapping_range(mapping, |
| 642 | (loff_t)index << PAGE_CACHE_SHIFT, |
| 643 | PAGE_CACHE_SIZE, 0); |
| 644 | } |
| 645 | } |
| 646 | BUG_ON(page_mapped(page)); |
| 647 | ret2 = do_launder_page(mapping, page); |
| 648 | if (ret2 == 0) { |
| 649 | if (!invalidate_complete_page2(mapping, page)) |
| 650 | ret2 = -EBUSY; |
| 651 | } |
| 652 | if (ret2 < 0) |
| 653 | ret = ret2; |
| 654 | unlock_page(page); |
| 655 | } |
| 656 | pagevec_remove_exceptionals(&pvec); |
| 657 | pagevec_release(&pvec); |
| 658 | mem_cgroup_uncharge_end(); |
| 659 | cond_resched(); |
| 660 | index++; |
| 661 | } |
| 662 | cleancache_invalidate_inode(mapping); |
| 663 | return ret; |
| 664 | } |
| 665 | EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range); |
| 666 | |
| 667 | /** |
| 668 | * invalidate_inode_pages2 - remove all pages from an address_space |
| 669 | * @mapping: the address_space |
| 670 | * |
| 671 | * Any pages which are found to be mapped into pagetables are unmapped prior to |
| 672 | * invalidation. |
| 673 | * |
| 674 | * Returns -EBUSY if any pages could not be invalidated. |
| 675 | */ |
| 676 | int invalidate_inode_pages2(struct address_space *mapping) |
| 677 | { |
| 678 | return invalidate_inode_pages2_range(mapping, 0, -1); |
| 679 | } |
| 680 | EXPORT_SYMBOL_GPL(invalidate_inode_pages2); |
| 681 | |
| 682 | /** |
| 683 | * truncate_pagecache - unmap and remove pagecache that has been truncated |
| 684 | * @inode: inode |
| 685 | * @newsize: new file size |
| 686 | * |
| 687 | * inode's new i_size must already be written before truncate_pagecache |
| 688 | * is called. |
| 689 | * |
| 690 | * This function should typically be called before the filesystem |
| 691 | * releases resources associated with the freed range (eg. deallocates |
| 692 | * blocks). This way, pagecache will always stay logically coherent |
| 693 | * with on-disk format, and the filesystem would not have to deal with |
| 694 | * situations such as writepage being called for a page that has already |
| 695 | * had its underlying blocks deallocated. |
| 696 | */ |
| 697 | void truncate_pagecache(struct inode *inode, loff_t newsize) |
| 698 | { |
| 699 | struct address_space *mapping = inode->i_mapping; |
| 700 | loff_t holebegin = round_up(newsize, PAGE_SIZE); |
| 701 | |
| 702 | /* |
| 703 | * unmap_mapping_range is called twice, first simply for |
| 704 | * efficiency so that truncate_inode_pages does fewer |
| 705 | * single-page unmaps. However after this first call, and |
| 706 | * before truncate_inode_pages finishes, it is possible for |
| 707 | * private pages to be COWed, which remain after |
| 708 | * truncate_inode_pages finishes, hence the second |
| 709 | * unmap_mapping_range call must be made for correctness. |
| 710 | */ |
| 711 | unmap_mapping_range(mapping, holebegin, 0, 1); |
| 712 | truncate_inode_pages(mapping, newsize); |
| 713 | unmap_mapping_range(mapping, holebegin, 0, 1); |
| 714 | } |
| 715 | EXPORT_SYMBOL(truncate_pagecache); |
| 716 | |
| 717 | /** |
| 718 | * truncate_setsize - update inode and pagecache for a new file size |
| 719 | * @inode: inode |
| 720 | * @newsize: new file size |
| 721 | * |
| 722 | * truncate_setsize updates i_size and performs pagecache truncation (if |
| 723 | * necessary) to @newsize. It will be typically be called from the filesystem's |
| 724 | * setattr function when ATTR_SIZE is passed in. |
| 725 | * |
| 726 | * Must be called with inode_mutex held and before all filesystem specific |
| 727 | * block truncation has been performed. |
| 728 | */ |
| 729 | void truncate_setsize(struct inode *inode, loff_t newsize) |
| 730 | { |
| 731 | i_size_write(inode, newsize); |
| 732 | truncate_pagecache(inode, newsize); |
| 733 | } |
| 734 | EXPORT_SYMBOL(truncate_setsize); |
| 735 | |
| 736 | /** |
| 737 | * truncate_pagecache_range - unmap and remove pagecache that is hole-punched |
| 738 | * @inode: inode |
| 739 | * @lstart: offset of beginning of hole |
| 740 | * @lend: offset of last byte of hole |
| 741 | * |
| 742 | * This function should typically be called before the filesystem |
| 743 | * releases resources associated with the freed range (eg. deallocates |
| 744 | * blocks). This way, pagecache will always stay logically coherent |
| 745 | * with on-disk format, and the filesystem would not have to deal with |
| 746 | * situations such as writepage being called for a page that has already |
| 747 | * had its underlying blocks deallocated. |
| 748 | */ |
| 749 | void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend) |
| 750 | { |
| 751 | struct address_space *mapping = inode->i_mapping; |
| 752 | loff_t unmap_start = round_up(lstart, PAGE_SIZE); |
| 753 | loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1; |
| 754 | /* |
| 755 | * This rounding is currently just for example: unmap_mapping_range |
| 756 | * expands its hole outwards, whereas we want it to contract the hole |
| 757 | * inwards. However, existing callers of truncate_pagecache_range are |
| 758 | * doing their own page rounding first. Note that unmap_mapping_range |
| 759 | * allows holelen 0 for all, and we allow lend -1 for end of file. |
| 760 | */ |
| 761 | |
| 762 | /* |
| 763 | * Unlike in truncate_pagecache, unmap_mapping_range is called only |
| 764 | * once (before truncating pagecache), and without "even_cows" flag: |
| 765 | * hole-punching should not remove private COWed pages from the hole. |
| 766 | */ |
| 767 | if ((u64)unmap_end > (u64)unmap_start) |
| 768 | unmap_mapping_range(mapping, unmap_start, |
| 769 | 1 + unmap_end - unmap_start, 0); |
| 770 | truncate_inode_pages_range(mapping, lstart, lend); |
| 771 | } |
| 772 | EXPORT_SYMBOL(truncate_pagecache_range); |