linux/mm/truncate.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * mm/truncate.c - code for taking down pages from address_spaces
   4 *
   5 * Copyright (C) 2002, Linus Torvalds
   6 *
   7 * 10Sep2002    Andrew Morton
   8 *              Initial version.
   9 */
  10
  11#include <linux/kernel.h>
  12#include <linux/backing-dev.h>
  13#include <linux/dax.h>
  14#include <linux/gfp.h>
  15#include <linux/mm.h>
  16#include <linux/swap.h>
  17#include <linux/export.h>
  18#include <linux/pagemap.h>
  19#include <linux/highmem.h>
  20#include <linux/pagevec.h>
  21#include <linux/task_io_accounting_ops.h>
  22#include <linux/buffer_head.h>  /* grr. try_to_release_page,
  23                                   do_invalidatepage */
  24#include <linux/shmem_fs.h>
  25#include <linux/cleancache.h>
  26#include <linux/rmap.h>
  27#include "internal.h"
  28
  29/*
  30 * Regular page slots are stabilized by the page lock even without the tree
  31 * itself locked.  These unlocked entries need verification under the tree
  32 * lock.
  33 */
  34static inline void __clear_shadow_entry(struct address_space *mapping,
  35                                pgoff_t index, void *entry)
  36{
  37        XA_STATE(xas, &mapping->i_pages, index);
  38
  39        xas_set_update(&xas, workingset_update_node);
  40        if (xas_load(&xas) != entry)
  41                return;
  42        xas_store(&xas, NULL);
  43}
  44
  45static void clear_shadow_entry(struct address_space *mapping, pgoff_t index,
  46                               void *entry)
  47{
  48        xa_lock_irq(&mapping->i_pages);
  49        __clear_shadow_entry(mapping, index, entry);
  50        xa_unlock_irq(&mapping->i_pages);
  51}
  52
  53/*
  54 * Unconditionally remove exceptional entries. Usually called from truncate
  55 * path. Note that the pagevec may be altered by this function by removing
  56 * exceptional entries similar to what pagevec_remove_exceptionals does.
  57 */
  58static void truncate_exceptional_pvec_entries(struct address_space *mapping,
  59                                struct pagevec *pvec, pgoff_t *indices)
  60{
  61        int i, j;
  62        bool dax;
  63
  64        /* Handled by shmem itself */
  65        if (shmem_mapping(mapping))
  66                return;
  67
  68        for (j = 0; j < pagevec_count(pvec); j++)
  69                if (xa_is_value(pvec->pages[j]))
  70                        break;
  71
  72        if (j == pagevec_count(pvec))
  73                return;
  74
  75        dax = dax_mapping(mapping);
  76        if (!dax)
  77                xa_lock_irq(&mapping->i_pages);
  78
  79        for (i = j; i < pagevec_count(pvec); i++) {
  80                struct page *page = pvec->pages[i];
  81                pgoff_t index = indices[i];
  82
  83                if (!xa_is_value(page)) {
  84                        pvec->pages[j++] = page;
  85                        continue;
  86                }
  87
  88                if (unlikely(dax)) {
  89                        dax_delete_mapping_entry(mapping, index);
  90                        continue;
  91                }
  92
  93                __clear_shadow_entry(mapping, index, page);
  94        }
  95
  96        if (!dax)
  97                xa_unlock_irq(&mapping->i_pages);
  98        pvec->nr = j;
  99}
 100
 101/*
 102 * Invalidate exceptional entry if easily possible. This handles exceptional
 103 * entries for invalidate_inode_pages().
 104 */
 105static int invalidate_exceptional_entry(struct address_space *mapping,
 106                                        pgoff_t index, void *entry)
 107{
 108        /* Handled by shmem itself, or for DAX we do nothing. */
 109        if (shmem_mapping(mapping) || dax_mapping(mapping))
 110                return 1;
 111        clear_shadow_entry(mapping, index, entry);
 112        return 1;
 113}
 114
 115/*
 116 * Invalidate exceptional entry if clean. This handles exceptional entries for
 117 * invalidate_inode_pages2() so for DAX it evicts only clean entries.
 118 */
 119static int invalidate_exceptional_entry2(struct address_space *mapping,
 120                                         pgoff_t index, void *entry)
 121{
 122        /* Handled by shmem itself */
 123        if (shmem_mapping(mapping))
 124                return 1;
 125        if (dax_mapping(mapping))
 126                return dax_invalidate_mapping_entry_sync(mapping, index);
 127        clear_shadow_entry(mapping, index, entry);
 128        return 1;
 129}
 130
 131/**
 132 * do_invalidatepage - invalidate part or all of a page
 133 * @page: the page which is affected
 134 * @offset: start of the range to invalidate
 135 * @length: length of the range to invalidate
 136 *
 137 * do_invalidatepage() is called when all or part of the page has become
 138 * invalidated by a truncate operation.
 139 *
 140 * do_invalidatepage() does not have to release all buffers, but it must
 141 * ensure that no dirty buffer is left outside @offset and that no I/O
 142 * is underway against any of the blocks which are outside the truncation
 143 * point.  Because the caller is about to free (and possibly reuse) those
 144 * blocks on-disk.
 145 */
 146void do_invalidatepage(struct page *page, unsigned int offset,
 147                       unsigned int length)
 148{
 149        void (*invalidatepage)(struct page *, unsigned int, unsigned int);
 150
 151        invalidatepage = page->mapping->a_ops->invalidatepage;
 152#ifdef CONFIG_BLOCK
 153        if (!invalidatepage)
 154                invalidatepage = block_invalidatepage;
 155#endif
 156        if (invalidatepage)
 157                (*invalidatepage)(page, offset, length);
 158}
 159
 160/*
 161 * If truncate cannot remove the fs-private metadata from the page, the page
 162 * becomes orphaned.  It will be left on the LRU and may even be mapped into
 163 * user pagetables if we're racing with filemap_fault().
 164 *
 165 * We need to bail out if page->mapping is no longer equal to the original
 166 * mapping.  This happens a) when the VM reclaimed the page while we waited on
 167 * its lock, b) when a concurrent invalidate_mapping_pages got there first and
 168 * c) when tmpfs swizzles a page between a tmpfs inode and swapper_space.
 169 */
 170static void truncate_cleanup_page(struct page *page)
 171{
 172        if (page_mapped(page))
 173                unmap_mapping_page(page);
 174
 175        if (page_has_private(page))
 176                do_invalidatepage(page, 0, thp_size(page));
 177
 178        /*
 179         * Some filesystems seem to re-dirty the page even after
 180         * the VM has canceled the dirty bit (eg ext3 journaling).
 181         * Hence dirty accounting check is placed after invalidation.
 182         */
 183        cancel_dirty_page(page);
 184        ClearPageMappedToDisk(page);
 185}
 186
 187/*
 188 * This is for invalidate_mapping_pages().  That function can be called at
 189 * any time, and is not supposed to throw away dirty pages.  But pages can
 190 * be marked dirty at any time too, so use remove_mapping which safely
 191 * discards clean, unused pages.
 192 *
 193 * Returns non-zero if the page was successfully invalidated.
 194 */
 195static int
 196invalidate_complete_page(struct address_space *mapping, struct page *page)
 197{
 198        int ret;
 199
 200        if (page->mapping != mapping)
 201                return 0;
 202
 203        if (page_has_private(page) && !try_to_release_page(page, 0))
 204                return 0;
 205
 206        ret = remove_mapping(mapping, page);
 207
 208        return ret;
 209}
 210
 211int truncate_inode_page(struct address_space *mapping, struct page *page)
 212{
 213        VM_BUG_ON_PAGE(PageTail(page), page);
 214
 215        if (page->mapping != mapping)
 216                return -EIO;
 217
 218        truncate_cleanup_page(page);
 219        delete_from_page_cache(page);
 220        return 0;
 221}
 222
 223/*
 224 * Used to get rid of pages on hardware memory corruption.
 225 */
 226int generic_error_remove_page(struct address_space *mapping, struct page *page)
 227{
 228        if (!mapping)
 229                return -EINVAL;
 230        /*
 231         * Only punch for normal data pages for now.
 232         * Handling other types like directories would need more auditing.
 233         */
 234        if (!S_ISREG(mapping->host->i_mode))
 235                return -EIO;
 236        return truncate_inode_page(mapping, page);
 237}
 238EXPORT_SYMBOL(generic_error_remove_page);
 239
 240/*
 241 * Safely invalidate one page from its pagecache mapping.
 242 * It only drops clean, unused pages. The page must be locked.
 243 *
 244 * Returns 1 if the page is successfully invalidated, otherwise 0.
 245 */
 246int invalidate_inode_page(struct page *page)
 247{
 248        struct address_space *mapping = page_mapping(page);
 249        if (!mapping)
 250                return 0;
 251        if (PageDirty(page) || PageWriteback(page))
 252                return 0;
 253        if (page_mapped(page))
 254                return 0;
 255        return invalidate_complete_page(mapping, page);
 256}
 257
 258/**
 259 * truncate_inode_pages_range - truncate range of pages specified by start & end byte offsets
 260 * @mapping: mapping to truncate
 261 * @lstart: offset from which to truncate
 262 * @lend: offset to which to truncate (inclusive)
 263 *
 264 * Truncate the page cache, removing the pages that are between
 265 * specified offsets (and zeroing out partial pages
 266 * if lstart or lend + 1 is not page aligned).
 267 *
 268 * Truncate takes two passes - the first pass is nonblocking.  It will not
 269 * block on page locks and it will not block on writeback.  The second pass
 270 * will wait.  This is to prevent as much IO as possible in the affected region.
 271 * The first pass will remove most pages, so the search cost of the second pass
 272 * is low.
 273 *
 274 * We pass down the cache-hot hint to the page freeing code.  Even if the
 275 * mapping is large, it is probably the case that the final pages are the most
 276 * recently touched, and freeing happens in ascending file offset order.
 277 *
 278 * Note that since ->invalidatepage() accepts range to invalidate
 279 * truncate_inode_pages_range is able to handle cases where lend + 1 is not
 280 * page aligned properly.
 281 */
 282void truncate_inode_pages_range(struct address_space *mapping,
 283                                loff_t lstart, loff_t lend)
 284{
 285        pgoff_t         start;          /* inclusive */
 286        pgoff_t         end;            /* exclusive */
 287        unsigned int    partial_start;  /* inclusive */
 288        unsigned int    partial_end;    /* exclusive */
 289        struct pagevec  pvec;
 290        pgoff_t         indices[PAGEVEC_SIZE];
 291        pgoff_t         index;
 292        int             i;
 293
 294        if (mapping_empty(mapping))
 295                goto out;
 296
 297        /* Offsets within partial pages */
 298        partial_start = lstart & (PAGE_SIZE - 1);
 299        partial_end = (lend + 1) & (PAGE_SIZE - 1);
 300
 301        /*
 302         * 'start' and 'end' always covers the range of pages to be fully
 303         * truncated. Partial pages are covered with 'partial_start' at the
 304         * start of the range and 'partial_end' at the end of the range.
 305         * Note that 'end' is exclusive while 'lend' is inclusive.
 306         */
 307        start = (lstart + PAGE_SIZE - 1) >> PAGE_SHIFT;
 308        if (lend == -1)
 309                /*
 310                 * lend == -1 indicates end-of-file so we have to set 'end'
 311                 * to the highest possible pgoff_t and since the type is
 312                 * unsigned we're using -1.
 313                 */
 314                end = -1;
 315        else
 316                end = (lend + 1) >> PAGE_SHIFT;
 317
 318        pagevec_init(&pvec);
 319        index = start;
 320        while (index < end && find_lock_entries(mapping, index, end - 1,
 321                        &pvec, indices)) {
 322                index = indices[pagevec_count(&pvec) - 1] + 1;
 323                truncate_exceptional_pvec_entries(mapping, &pvec, indices);
 324                for (i = 0; i < pagevec_count(&pvec); i++)
 325                        truncate_cleanup_page(pvec.pages[i]);
 326                delete_from_page_cache_batch(mapping, &pvec);
 327                for (i = 0; i < pagevec_count(&pvec); i++)
 328                        unlock_page(pvec.pages[i]);
 329                pagevec_release(&pvec);
 330                cond_resched();
 331        }
 332
 333        if (partial_start) {
 334                struct page *page = find_lock_page(mapping, start - 1);
 335                if (page) {
 336                        unsigned int top = PAGE_SIZE;
 337                        if (start > end) {
 338                                /* Truncation within a single page */
 339                                top = partial_end;
 340                                partial_end = 0;
 341                        }
 342                        wait_on_page_writeback(page);
 343                        zero_user_segment(page, partial_start, top);
 344                        cleancache_invalidate_page(mapping, page);
 345                        if (page_has_private(page))
 346                                do_invalidatepage(page, partial_start,
 347                                                  top - partial_start);
 348                        unlock_page(page);
 349                        put_page(page);
 350                }
 351        }
 352        if (partial_end) {
 353                struct page *page = find_lock_page(mapping, end);
 354                if (page) {
 355                        wait_on_page_writeback(page);
 356                        zero_user_segment(page, 0, partial_end);
 357                        cleancache_invalidate_page(mapping, page);
 358                        if (page_has_private(page))
 359                                do_invalidatepage(page, 0,
 360                                                  partial_end);
 361                        unlock_page(page);
 362                        put_page(page);
 363                }
 364        }
 365        /*
 366         * If the truncation happened within a single page no pages
 367         * will be released, just zeroed, so we can bail out now.
 368         */
 369        if (start >= end)
 370                goto out;
 371
 372        index = start;
 373        for ( ; ; ) {
 374                cond_resched();
 375                if (!find_get_entries(mapping, index, end - 1, &pvec,
 376                                indices)) {
 377                        /* If all gone from start onwards, we're done */
 378                        if (index == start)
 379                                break;
 380                        /* Otherwise restart to make sure all gone */
 381                        index = start;
 382                        continue;
 383                }
 384
 385                for (i = 0; i < pagevec_count(&pvec); i++) {
 386                        struct page *page = pvec.pages[i];
 387
 388                        /* We rely upon deletion not changing page->index */
 389                        index = indices[i];
 390
 391                        if (xa_is_value(page))
 392                                continue;
 393
 394                        lock_page(page);
 395                        WARN_ON(page_to_index(page) != index);
 396                        wait_on_page_writeback(page);
 397                        truncate_inode_page(mapping, page);
 398                        unlock_page(page);
 399                }
 400                truncate_exceptional_pvec_entries(mapping, &pvec, indices);
 401                pagevec_release(&pvec);
 402                index++;
 403        }
 404
 405out:
 406        cleancache_invalidate_inode(mapping);
 407}
 408EXPORT_SYMBOL(truncate_inode_pages_range);
 409
 410/**
 411 * truncate_inode_pages - truncate *all* the pages from an offset
 412 * @mapping: mapping to truncate
 413 * @lstart: offset from which to truncate
 414 *
 415 * Called under (and serialised by) inode->i_mutex.
 416 *
 417 * Note: When this function returns, there can be a page in the process of
 418 * deletion (inside __delete_from_page_cache()) in the specified range.  Thus
 419 * mapping->nrpages can be non-zero when this function returns even after
 420 * truncation of the whole mapping.
 421 */
 422void truncate_inode_pages(struct address_space *mapping, loff_t lstart)
 423{
 424        truncate_inode_pages_range(mapping, lstart, (loff_t)-1);
 425}
 426EXPORT_SYMBOL(truncate_inode_pages);
 427
 428/**
 429 * truncate_inode_pages_final - truncate *all* pages before inode dies
 430 * @mapping: mapping to truncate
 431 *
 432 * Called under (and serialized by) inode->i_mutex.
 433 *
 434 * Filesystems have to use this in the .evict_inode path to inform the
 435 * VM that this is the final truncate and the inode is going away.
 436 */
 437void truncate_inode_pages_final(struct address_space *mapping)
 438{
 439        /*
 440         * Page reclaim can not participate in regular inode lifetime
 441         * management (can't call iput()) and thus can race with the
 442         * inode teardown.  Tell it when the address space is exiting,
 443         * so that it does not install eviction information after the
 444         * final truncate has begun.
 445         */
 446        mapping_set_exiting(mapping);
 447
 448        if (!mapping_empty(mapping)) {
 449                /*
 450                 * As truncation uses a lockless tree lookup, cycle
 451                 * the tree lock to make sure any ongoing tree
 452                 * modification that does not see AS_EXITING is
 453                 * completed before starting the final truncate.
 454                 */
 455                xa_lock_irq(&mapping->i_pages);
 456                xa_unlock_irq(&mapping->i_pages);
 457        }
 458
 459        /*
 460         * Cleancache needs notification even if there are no pages or shadow
 461         * entries.
 462         */
 463        truncate_inode_pages(mapping, 0);
 464}
 465EXPORT_SYMBOL(truncate_inode_pages_final);
 466
 467static unsigned long __invalidate_mapping_pages(struct address_space *mapping,
 468                pgoff_t start, pgoff_t end, unsigned long *nr_pagevec)
 469{
 470        pgoff_t indices[PAGEVEC_SIZE];
 471        struct pagevec pvec;
 472        pgoff_t index = start;
 473        unsigned long ret;
 474        unsigned long count = 0;
 475        int i;
 476
 477        pagevec_init(&pvec);
 478        while (find_lock_entries(mapping, index, end, &pvec, indices)) {
 479                for (i = 0; i < pagevec_count(&pvec); i++) {
 480                        struct page *page = pvec.pages[i];
 481
 482                        /* We rely upon deletion not changing page->index */
 483                        index = indices[i];
 484
 485                        if (xa_is_value(page)) {
 486                                invalidate_exceptional_entry(mapping, index,
 487                                                             page);
 488                                continue;
 489                        }
 490                        index += thp_nr_pages(page) - 1;
 491
 492                        ret = invalidate_inode_page(page);
 493                        unlock_page(page);
 494                        /*
 495                         * Invalidation is a hint that the page is no longer
 496                         * of interest and try to speed up its reclaim.
 497                         */
 498                        if (!ret) {
 499                                deactivate_file_page(page);
 500                                /* It is likely on the pagevec of a remote CPU */
 501                                if (nr_pagevec)
 502                                        (*nr_pagevec)++;
 503                        }
 504                        count += ret;
 505                }
 506                pagevec_remove_exceptionals(&pvec);
 507                pagevec_release(&pvec);
 508                cond_resched();
 509                index++;
 510        }
 511        return count;
 512}
 513
 514/**
 515 * invalidate_mapping_pages - Invalidate all the unlocked pages of one inode
 516 * @mapping: the address_space which holds the pages to invalidate
 517 * @start: the offset 'from' which to invalidate
 518 * @end: the offset 'to' which to invalidate (inclusive)
 519 *
 520 * This function only removes the unlocked pages, if you want to
 521 * remove all the pages of one inode, you must call truncate_inode_pages.
 522 *
 523 * invalidate_mapping_pages() will not block on IO activity. It will not
 524 * invalidate pages which are dirty, locked, under writeback or mapped into
 525 * pagetables.
 526 *
 527 * Return: the number of the pages that were invalidated
 528 */
 529unsigned long invalidate_mapping_pages(struct address_space *mapping,
 530                pgoff_t start, pgoff_t end)
 531{
 532        return __invalidate_mapping_pages(mapping, start, end, NULL);
 533}
 534EXPORT_SYMBOL(invalidate_mapping_pages);
 535
 536/**
 537 * invalidate_mapping_pagevec - Invalidate all the unlocked pages of one inode
 538 * @mapping: the address_space which holds the pages to invalidate
 539 * @start: the offset 'from' which to invalidate
 540 * @end: the offset 'to' which to invalidate (inclusive)
 541 * @nr_pagevec: invalidate failed page number for caller
 542 *
 543 * This helper is similar to invalidate_mapping_pages(), except that it accounts
 544 * for pages that are likely on a pagevec and counts them in @nr_pagevec, which
 545 * will be used by the caller.
 546 */
 547void invalidate_mapping_pagevec(struct address_space *mapping,
 548                pgoff_t start, pgoff_t end, unsigned long *nr_pagevec)
 549{
 550        __invalidate_mapping_pages(mapping, start, end, nr_pagevec);
 551}
 552
 553/*
 554 * This is like invalidate_complete_page(), except it ignores the page's
 555 * refcount.  We do this because invalidate_inode_pages2() needs stronger
 556 * invalidation guarantees, and cannot afford to leave pages behind because
 557 * shrink_page_list() has a temp ref on them, or because they're transiently
 558 * sitting in the lru_cache_add() pagevecs.
 559 */
 560static int
 561invalidate_complete_page2(struct address_space *mapping, struct page *page)
 562{
 563        unsigned long flags;
 564
 565        if (page->mapping != mapping)
 566                return 0;
 567
 568        if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
 569                return 0;
 570
 571        xa_lock_irqsave(&mapping->i_pages, flags);
 572        if (PageDirty(page))
 573                goto failed;
 574
 575        BUG_ON(page_has_private(page));
 576        __delete_from_page_cache(page, NULL);
 577        xa_unlock_irqrestore(&mapping->i_pages, flags);
 578
 579        if (mapping->a_ops->freepage)
 580                mapping->a_ops->freepage(page);
 581
 582        put_page(page); /* pagecache ref */
 583        return 1;
 584failed:
 585        xa_unlock_irqrestore(&mapping->i_pages, flags);
 586        return 0;
 587}
 588
 589static int do_launder_page(struct address_space *mapping, struct page *page)
 590{
 591        if (!PageDirty(page))
 592                return 0;
 593        if (page->mapping != mapping || mapping->a_ops->launder_page == NULL)
 594                return 0;
 595        return mapping->a_ops->launder_page(page);
 596}
 597
 598/**
 599 * invalidate_inode_pages2_range - remove range of pages from an address_space
 600 * @mapping: the address_space
 601 * @start: the page offset 'from' which to invalidate
 602 * @end: the page offset 'to' which to invalidate (inclusive)
 603 *
 604 * Any pages which are found to be mapped into pagetables are unmapped prior to
 605 * invalidation.
 606 *
 607 * Return: -EBUSY if any pages could not be invalidated.
 608 */
 609int invalidate_inode_pages2_range(struct address_space *mapping,
 610                                  pgoff_t start, pgoff_t end)
 611{
 612        pgoff_t indices[PAGEVEC_SIZE];
 613        struct pagevec pvec;
 614        pgoff_t index;
 615        int i;
 616        int ret = 0;
 617        int ret2 = 0;
 618        int did_range_unmap = 0;
 619
 620        if (mapping_empty(mapping))
 621                goto out;
 622
 623        pagevec_init(&pvec);
 624        index = start;
 625        while (find_get_entries(mapping, index, end, &pvec, indices)) {
 626                for (i = 0; i < pagevec_count(&pvec); i++) {
 627                        struct page *page = pvec.pages[i];
 628
 629                        /* We rely upon deletion not changing page->index */
 630                        index = indices[i];
 631
 632                        if (xa_is_value(page)) {
 633                                if (!invalidate_exceptional_entry2(mapping,
 634                                                                   index, page))
 635                                        ret = -EBUSY;
 636                                continue;
 637                        }
 638
 639                        if (!did_range_unmap && page_mapped(page)) {
 640                                /*
 641                                 * If page is mapped, before taking its lock,
 642                                 * zap the rest of the file in one hit.
 643                                 */
 644                                unmap_mapping_pages(mapping, index,
 645                                                (1 + end - index), false);
 646                                did_range_unmap = 1;
 647                        }
 648
 649                        lock_page(page);
 650                        WARN_ON(page_to_index(page) != index);
 651                        if (page->mapping != mapping) {
 652                                unlock_page(page);
 653                                continue;
 654                        }
 655                        wait_on_page_writeback(page);
 656
 657                        if (page_mapped(page))
 658                                unmap_mapping_page(page);
 659                        BUG_ON(page_mapped(page));
 660
 661                        ret2 = do_launder_page(mapping, page);
 662                        if (ret2 == 0) {
 663                                if (!invalidate_complete_page2(mapping, page))
 664                                        ret2 = -EBUSY;
 665                        }
 666                        if (ret2 < 0)
 667                                ret = ret2;
 668                        unlock_page(page);
 669                }
 670                pagevec_remove_exceptionals(&pvec);
 671                pagevec_release(&pvec);
 672                cond_resched();
 673                index++;
 674        }
 675        /*
 676         * For DAX we invalidate page tables after invalidating page cache.  We
 677         * could invalidate page tables while invalidating each entry however
 678         * that would be expensive. And doing range unmapping before doesn't
 679         * work as we have no cheap way to find whether page cache entry didn't
 680         * get remapped later.
 681         */
 682        if (dax_mapping(mapping)) {
 683                unmap_mapping_pages(mapping, start, end - start + 1, false);
 684        }
 685out:
 686        cleancache_invalidate_inode(mapping);
 687        return ret;
 688}
 689EXPORT_SYMBOL_GPL(invalidate_inode_pages2_range);
 690
 691/**
 692 * invalidate_inode_pages2 - remove all pages from an address_space
 693 * @mapping: the address_space
 694 *
 695 * Any pages which are found to be mapped into pagetables are unmapped prior to
 696 * invalidation.
 697 *
 698 * Return: -EBUSY if any pages could not be invalidated.
 699 */
 700int invalidate_inode_pages2(struct address_space *mapping)
 701{
 702        return invalidate_inode_pages2_range(mapping, 0, -1);
 703}
 704EXPORT_SYMBOL_GPL(invalidate_inode_pages2);
 705
 706/**
 707 * truncate_pagecache - unmap and remove pagecache that has been truncated
 708 * @inode: inode
 709 * @newsize: new file size
 710 *
 711 * inode's new i_size must already be written before truncate_pagecache
 712 * is called.
 713 *
 714 * This function should typically be called before the filesystem
 715 * releases resources associated with the freed range (eg. deallocates
 716 * blocks). This way, pagecache will always stay logically coherent
 717 * with on-disk format, and the filesystem would not have to deal with
 718 * situations such as writepage being called for a page that has already
 719 * had its underlying blocks deallocated.
 720 */
 721void truncate_pagecache(struct inode *inode, loff_t newsize)
 722{
 723        struct address_space *mapping = inode->i_mapping;
 724        loff_t holebegin = round_up(newsize, PAGE_SIZE);
 725
 726        /*
 727         * unmap_mapping_range is called twice, first simply for
 728         * efficiency so that truncate_inode_pages does fewer
 729         * single-page unmaps.  However after this first call, and
 730         * before truncate_inode_pages finishes, it is possible for
 731         * private pages to be COWed, which remain after
 732         * truncate_inode_pages finishes, hence the second
 733         * unmap_mapping_range call must be made for correctness.
 734         */
 735        unmap_mapping_range(mapping, holebegin, 0, 1);
 736        truncate_inode_pages(mapping, newsize);
 737        unmap_mapping_range(mapping, holebegin, 0, 1);
 738}
 739EXPORT_SYMBOL(truncate_pagecache);
 740
 741/**
 742 * truncate_setsize - update inode and pagecache for a new file size
 743 * @inode: inode
 744 * @newsize: new file size
 745 *
 746 * truncate_setsize updates i_size and performs pagecache truncation (if
 747 * necessary) to @newsize. It will be typically be called from the filesystem's
 748 * setattr function when ATTR_SIZE is passed in.
 749 *
 750 * Must be called with a lock serializing truncates and writes (generally
 751 * i_mutex but e.g. xfs uses a different lock) and before all filesystem
 752 * specific block truncation has been performed.
 753 */
 754void truncate_setsize(struct inode *inode, loff_t newsize)
 755{
 756        loff_t oldsize = inode->i_size;
 757
 758        i_size_write(inode, newsize);
 759        if (newsize > oldsize)
 760                pagecache_isize_extended(inode, oldsize, newsize);
 761        truncate_pagecache(inode, newsize);
 762}
 763EXPORT_SYMBOL(truncate_setsize);
 764
 765/**
 766 * pagecache_isize_extended - update pagecache after extension of i_size
 767 * @inode:      inode for which i_size was extended
 768 * @from:       original inode size
 769 * @to:         new inode size
 770 *
 771 * Handle extension of inode size either caused by extending truncate or by
 772 * write starting after current i_size. We mark the page straddling current
 773 * i_size RO so that page_mkwrite() is called on the nearest write access to
 774 * the page.  This way filesystem can be sure that page_mkwrite() is called on
 775 * the page before user writes to the page via mmap after the i_size has been
 776 * changed.
 777 *
 778 * The function must be called after i_size is updated so that page fault
 779 * coming after we unlock the page will already see the new i_size.
 780 * The function must be called while we still hold i_mutex - this not only
 781 * makes sure i_size is stable but also that userspace cannot observe new
 782 * i_size value before we are prepared to store mmap writes at new inode size.
 783 */
 784void pagecache_isize_extended(struct inode *inode, loff_t from, loff_t to)
 785{
 786        int bsize = i_blocksize(inode);
 787        loff_t rounded_from;
 788        struct page *page;
 789        pgoff_t index;
 790
 791        WARN_ON(to > inode->i_size);
 792
 793        if (from >= to || bsize == PAGE_SIZE)
 794                return;
 795        /* Page straddling @from will not have any hole block created? */
 796        rounded_from = round_up(from, bsize);
 797        if (to <= rounded_from || !(rounded_from & (PAGE_SIZE - 1)))
 798                return;
 799
 800        index = from >> PAGE_SHIFT;
 801        page = find_lock_page(inode->i_mapping, index);
 802        /* Page not cached? Nothing to do */
 803        if (!page)
 804                return;
 805        /*
 806         * See clear_page_dirty_for_io() for details why set_page_dirty()
 807         * is needed.
 808         */
 809        if (page_mkclean(page))
 810                set_page_dirty(page);
 811        unlock_page(page);
 812        put_page(page);
 813}
 814EXPORT_SYMBOL(pagecache_isize_extended);
 815
 816/**
 817 * truncate_pagecache_range - unmap and remove pagecache that is hole-punched
 818 * @inode: inode
 819 * @lstart: offset of beginning of hole
 820 * @lend: offset of last byte of hole
 821 *
 822 * This function should typically be called before the filesystem
 823 * releases resources associated with the freed range (eg. deallocates
 824 * blocks). This way, pagecache will always stay logically coherent
 825 * with on-disk format, and the filesystem would not have to deal with
 826 * situations such as writepage being called for a page that has already
 827 * had its underlying blocks deallocated.
 828 */
 829void truncate_pagecache_range(struct inode *inode, loff_t lstart, loff_t lend)
 830{
 831        struct address_space *mapping = inode->i_mapping;
 832        loff_t unmap_start = round_up(lstart, PAGE_SIZE);
 833        loff_t unmap_end = round_down(1 + lend, PAGE_SIZE) - 1;
 834        /*
 835         * This rounding is currently just for example: unmap_mapping_range
 836         * expands its hole outwards, whereas we want it to contract the hole
 837         * inwards.  However, existing callers of truncate_pagecache_range are
 838         * doing their own page rounding first.  Note that unmap_mapping_range
 839         * allows holelen 0 for all, and we allow lend -1 for end of file.
 840         */
 841
 842        /*
 843         * Unlike in truncate_pagecache, unmap_mapping_range is called only
 844         * once (before truncating pagecache), and without "even_cows" flag:
 845         * hole-punching should not remove private COWed pages from the hole.
 846         */
 847        if ((u64)unmap_end > (u64)unmap_start)
 848                unmap_mapping_range(mapping, unmap_start,
 849                                    1 + unmap_end - unmap_start, 0);
 850        truncate_inode_pages_range(mapping, lstart, lend);
 851}
 852EXPORT_SYMBOL(truncate_pagecache_range);
 853
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