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1// SPDX-License-Identifier: GPL-2.0-only2/*3 * linux/mm/filemap.c4 *5 * Copyright (C) 1994-1999 Linus Torvalds6 */7 8/*9 * This file handles the generic file mmap semantics used by10 * most "normal" filesystems (but you don't /have/ to use this:11 * the NFS filesystem used to do this differently, for example)12 */13#include <linux/export.h>14#include <linux/compiler.h>15#include <linux/dax.h>16#include <linux/fs.h>17#include <linux/sched/signal.h>18#include <linux/uaccess.h>19#include <linux/capability.h>20#include <linux/kernel_stat.h>21#include <linux/gfp.h>22#include <linux/mm.h>23#include <linux/swap.h>24#include <linux/swapops.h>25#include <linux/syscalls.h>26#include <linux/mman.h>27#include <linux/pagemap.h>28#include <linux/file.h>29#include <linux/uio.h>30#include <linux/error-injection.h>31#include <linux/hash.h>32#include <linux/writeback.h>33#include <linux/backing-dev.h>34#include <linux/pagevec.h>35#include <linux/security.h>36#include <linux/cpuset.h>37#include <linux/hugetlb.h>38#include <linux/memcontrol.h>39#include <linux/shmem_fs.h>40#include <linux/rmap.h>41#include <linux/delayacct.h>42#include <linux/psi.h>43#include <linux/ramfs.h>44#include <linux/page_idle.h>45#include <linux/migrate.h>46#include <linux/pipe_fs_i.h>47#include <linux/splice.h>48#include <linux/rcupdate_wait.h>49#include <linux/sched/mm.h>50#include <asm/pgalloc.h>51#include <asm/tlbflush.h>52#include "internal.h"53 54#define CREATE_TRACE_POINTS55#include <trace/events/filemap.h>56 57/*58 * FIXME: remove all knowledge of the buffer layer from the core VM59 */60#include <linux/buffer_head.h> /* for try_to_free_buffers */61 62#include <asm/mman.h>63 64#include "swap.h"65 66/*67 * Shared mappings implemented 30.11.1994. It's not fully working yet,68 * though.69 *70 * Shared mappings now work. 15.8.1995 Bruno.71 *72 * finished 'unifying' the page and buffer cache and SMP-threaded the73 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>74 *75 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>76 */77 78/*79 * Lock ordering:80 *81 * ->i_mmap_rwsem (truncate_pagecache)82 * ->private_lock (__free_pte->block_dirty_folio)83 * ->swap_lock (exclusive_swap_page, others)84 * ->i_pages lock85 *86 * ->i_rwsem87 * ->invalidate_lock (acquired by fs in truncate path)88 * ->i_mmap_rwsem (truncate->unmap_mapping_range)89 *90 * ->mmap_lock91 * ->i_mmap_rwsem92 * ->page_table_lock or pte_lock (various, mainly in memory.c)93 * ->i_pages lock (arch-dependent flush_dcache_mmap_lock)94 *95 * ->mmap_lock96 * ->invalidate_lock (filemap_fault)97 * ->lock_page (filemap_fault, access_process_vm)98 *99 * ->i_rwsem (generic_perform_write)100 * ->mmap_lock (fault_in_readable->do_page_fault)101 *102 * bdi->wb.list_lock103 * sb_lock (fs/fs-writeback.c)104 * ->i_pages lock (__sync_single_inode)105 *106 * ->i_mmap_rwsem107 * ->anon_vma.lock (vma_merge)108 *109 * ->anon_vma.lock110 * ->page_table_lock or pte_lock (anon_vma_prepare and various)111 *112 * ->page_table_lock or pte_lock113 * ->swap_lock (try_to_unmap_one)114 * ->private_lock (try_to_unmap_one)115 * ->i_pages lock (try_to_unmap_one)116 * ->lruvec->lru_lock (follow_page_mask->mark_page_accessed)117 * ->lruvec->lru_lock (check_pte_range->folio_isolate_lru)118 * ->private_lock (folio_remove_rmap_pte->set_page_dirty)119 * ->i_pages lock (folio_remove_rmap_pte->set_page_dirty)120 * bdi.wb->list_lock (folio_remove_rmap_pte->set_page_dirty)121 * ->inode->i_lock (folio_remove_rmap_pte->set_page_dirty)122 * ->memcg->move_lock (folio_remove_rmap_pte->folio_memcg_lock)123 * bdi.wb->list_lock (zap_pte_range->set_page_dirty)124 * ->inode->i_lock (zap_pte_range->set_page_dirty)125 * ->private_lock (zap_pte_range->block_dirty_folio)126 */127 128static void mapping_set_update(struct xa_state *xas,129 struct address_space *mapping)130{131 if (dax_mapping(mapping) || shmem_mapping(mapping))132 return;133 xas_set_update(xas, workingset_update_node);134 xas_set_lru(xas, &shadow_nodes);135}136 137static void page_cache_delete(struct address_space *mapping,138 struct folio *folio, void *shadow)139{140 XA_STATE(xas, &mapping->i_pages, folio->index);141 long nr = 1;142 143 mapping_set_update(&xas, mapping);144 145 xas_set_order(&xas, folio->index, folio_order(folio));146 nr = folio_nr_pages(folio);147 148 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);149 150 xas_store(&xas, shadow);151 xas_init_marks(&xas);152 153 folio->mapping = NULL;154 /* Leave page->index set: truncation lookup relies upon it */155 mapping->nrpages -= nr;156}157 158static void filemap_unaccount_folio(struct address_space *mapping,159 struct folio *folio)160{161 long nr;162 163 VM_BUG_ON_FOLIO(folio_mapped(folio), folio);164 if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(folio_mapped(folio))) {165 pr_alert("BUG: Bad page cache in process %s pfn:%05lx\n",166 current->comm, folio_pfn(folio));167 dump_page(&folio->page, "still mapped when deleted");168 dump_stack();169 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);170 171 if (mapping_exiting(mapping) && !folio_test_large(folio)) {172 int mapcount = folio_mapcount(folio);173 174 if (folio_ref_count(folio) >= mapcount + 2) {175 /*176 * All vmas have already been torn down, so it's177 * a good bet that actually the page is unmapped178 * and we'd rather not leak it: if we're wrong,179 * another bad page check should catch it later.180 */181 atomic_set(&folio->_mapcount, -1);182 folio_ref_sub(folio, mapcount);183 }184 }185 }186 187 /* hugetlb folios do not participate in page cache accounting. */188 if (folio_test_hugetlb(folio))189 return;190 191 nr = folio_nr_pages(folio);192 193 __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, -nr);194 if (folio_test_swapbacked(folio)) {195 __lruvec_stat_mod_folio(folio, NR_SHMEM, -nr);196 if (folio_test_pmd_mappable(folio))197 __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, -nr);198 } else if (folio_test_pmd_mappable(folio)) {199 __lruvec_stat_mod_folio(folio, NR_FILE_THPS, -nr);200 filemap_nr_thps_dec(mapping);201 }202 203 /*204 * At this point folio must be either written or cleaned by205 * truncate. Dirty folio here signals a bug and loss of206 * unwritten data - on ordinary filesystems.207 *208 * But it's harmless on in-memory filesystems like tmpfs; and can209 * occur when a driver which did get_user_pages() sets page dirty210 * before putting it, while the inode is being finally evicted.211 *212 * Below fixes dirty accounting after removing the folio entirely213 * but leaves the dirty flag set: it has no effect for truncated214 * folio and anyway will be cleared before returning folio to215 * buddy allocator.216 */217 if (WARN_ON_ONCE(folio_test_dirty(folio) &&218 mapping_can_writeback(mapping)))219 folio_account_cleaned(folio, inode_to_wb(mapping->host));220}221 222/*223 * Delete a page from the page cache and free it. Caller has to make224 * sure the page is locked and that nobody else uses it - or that usage225 * is safe. The caller must hold the i_pages lock.226 */227void __filemap_remove_folio(struct folio *folio, void *shadow)228{229 struct address_space *mapping = folio->mapping;230 231 trace_mm_filemap_delete_from_page_cache(folio);232 filemap_unaccount_folio(mapping, folio);233 page_cache_delete(mapping, folio, shadow);234}235 236void filemap_free_folio(struct address_space *mapping, struct folio *folio)237{238 void (*free_folio)(struct folio *);239 int refs = 1;240 241 free_folio = mapping->a_ops->free_folio;242 if (free_folio)243 free_folio(folio);244 245 if (folio_test_large(folio))246 refs = folio_nr_pages(folio);247 folio_put_refs(folio, refs);248}249 250/**251 * filemap_remove_folio - Remove folio from page cache.252 * @folio: The folio.253 *254 * This must be called only on folios that are locked and have been255 * verified to be in the page cache. It will never put the folio into256 * the free list because the caller has a reference on the page.257 */258void filemap_remove_folio(struct folio *folio)259{260 struct address_space *mapping = folio->mapping;261 262 BUG_ON(!folio_test_locked(folio));263 spin_lock(&mapping->host->i_lock);264 xa_lock_irq(&mapping->i_pages);265 __filemap_remove_folio(folio, NULL);266 xa_unlock_irq(&mapping->i_pages);267 if (mapping_shrinkable(mapping))268 inode_add_lru(mapping->host);269 spin_unlock(&mapping->host->i_lock);270 271 filemap_free_folio(mapping, folio);272}273 274/*275 * page_cache_delete_batch - delete several folios from page cache276 * @mapping: the mapping to which folios belong277 * @fbatch: batch of folios to delete278 *279 * The function walks over mapping->i_pages and removes folios passed in280 * @fbatch from the mapping. The function expects @fbatch to be sorted281 * by page index and is optimised for it to be dense.282 * It tolerates holes in @fbatch (mapping entries at those indices are not283 * modified).284 *285 * The function expects the i_pages lock to be held.286 */287static void page_cache_delete_batch(struct address_space *mapping,288 struct folio_batch *fbatch)289{290 XA_STATE(xas, &mapping->i_pages, fbatch->folios[0]->index);291 long total_pages = 0;292 int i = 0;293 struct folio *folio;294 295 mapping_set_update(&xas, mapping);296 xas_for_each(&xas, folio, ULONG_MAX) {297 if (i >= folio_batch_count(fbatch))298 break;299 300 /* A swap/dax/shadow entry got inserted? Skip it. */301 if (xa_is_value(folio))302 continue;303 /*304 * A page got inserted in our range? Skip it. We have our305 * pages locked so they are protected from being removed.306 * If we see a page whose index is higher than ours, it307 * means our page has been removed, which shouldn't be308 * possible because we're holding the PageLock.309 */310 if (folio != fbatch->folios[i]) {311 VM_BUG_ON_FOLIO(folio->index >312 fbatch->folios[i]->index, folio);313 continue;314 }315 316 WARN_ON_ONCE(!folio_test_locked(folio));317 318 folio->mapping = NULL;319 /* Leave folio->index set: truncation lookup relies on it */320 321 i++;322 xas_store(&xas, NULL);323 total_pages += folio_nr_pages(folio);324 }325 mapping->nrpages -= total_pages;326}327 328void delete_from_page_cache_batch(struct address_space *mapping,329 struct folio_batch *fbatch)330{331 int i;332 333 if (!folio_batch_count(fbatch))334 return;335 336 spin_lock(&mapping->host->i_lock);337 xa_lock_irq(&mapping->i_pages);338 for (i = 0; i < folio_batch_count(fbatch); i++) {339 struct folio *folio = fbatch->folios[i];340 341 trace_mm_filemap_delete_from_page_cache(folio);342 filemap_unaccount_folio(mapping, folio);343 }344 page_cache_delete_batch(mapping, fbatch);345 xa_unlock_irq(&mapping->i_pages);346 if (mapping_shrinkable(mapping))347 inode_add_lru(mapping->host);348 spin_unlock(&mapping->host->i_lock);349 350 for (i = 0; i < folio_batch_count(fbatch); i++)351 filemap_free_folio(mapping, fbatch->folios[i]);352}353 354int filemap_check_errors(struct address_space *mapping)355{356 int ret = 0;357 /* Check for outstanding write errors */358 if (test_bit(AS_ENOSPC, &mapping->flags) &&359 test_and_clear_bit(AS_ENOSPC, &mapping->flags))360 ret = -ENOSPC;361 if (test_bit(AS_EIO, &mapping->flags) &&362 test_and_clear_bit(AS_EIO, &mapping->flags))363 ret = -EIO;364 return ret;365}366EXPORT_SYMBOL(filemap_check_errors);367 368static int filemap_check_and_keep_errors(struct address_space *mapping)369{370 /* Check for outstanding write errors */371 if (test_bit(AS_EIO, &mapping->flags))372 return -EIO;373 if (test_bit(AS_ENOSPC, &mapping->flags))374 return -ENOSPC;375 return 0;376}377 378/**379 * filemap_fdatawrite_wbc - start writeback on mapping dirty pages in range380 * @mapping: address space structure to write381 * @wbc: the writeback_control controlling the writeout382 *383 * Call writepages on the mapping using the provided wbc to control the384 * writeout.385 *386 * Return: %0 on success, negative error code otherwise.387 */388int filemap_fdatawrite_wbc(struct address_space *mapping,389 struct writeback_control *wbc)390{391 int ret;392 393 if (!mapping_can_writeback(mapping) ||394 !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))395 return 0;396 397 wbc_attach_fdatawrite_inode(wbc, mapping->host);398 ret = do_writepages(mapping, wbc);399 wbc_detach_inode(wbc);400 return ret;401}402EXPORT_SYMBOL(filemap_fdatawrite_wbc);403 404/**405 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range406 * @mapping: address space structure to write407 * @start: offset in bytes where the range starts408 * @end: offset in bytes where the range ends (inclusive)409 * @sync_mode: enable synchronous operation410 *411 * Start writeback against all of a mapping's dirty pages that lie412 * within the byte offsets <start, end> inclusive.413 *414 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as415 * opposed to a regular memory cleansing writeback. The difference between416 * these two operations is that if a dirty page/buffer is encountered, it must417 * be waited upon, and not just skipped over.418 *419 * Return: %0 on success, negative error code otherwise.420 */421int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,422 loff_t end, int sync_mode)423{424 struct writeback_control wbc = {425 .sync_mode = sync_mode,426 .nr_to_write = LONG_MAX,427 .range_start = start,428 .range_end = end,429 };430 431 return filemap_fdatawrite_wbc(mapping, &wbc);432}433 434static HWJS_SUSPENDS inline int __filemap_fdatawrite(struct address_space *mapping,435 int sync_mode)436{437 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);438}439 440int filemap_fdatawrite(struct address_space *mapping)441{442 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);443}444EXPORT_SYMBOL(filemap_fdatawrite);445 446int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,447 loff_t end)448{449 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);450}451EXPORT_SYMBOL(filemap_fdatawrite_range);452 453/**454 * filemap_flush - mostly a non-blocking flush455 * @mapping: target address_space456 *457 * This is a mostly non-blocking flush. Not suitable for data-integrity458 * purposes - I/O may not be started against all dirty pages.459 *460 * Return: %0 on success, negative error code otherwise.461 */462int filemap_flush(struct address_space *mapping)463{464 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);465}466EXPORT_SYMBOL(filemap_flush);467 468/**469 * filemap_range_has_page - check if a page exists in range.470 * @mapping: address space within which to check471 * @start_byte: offset in bytes where the range starts472 * @end_byte: offset in bytes where the range ends (inclusive)473 *474 * Find at least one page in the range supplied, usually used to check if475 * direct writing in this range will trigger a writeback.476 *477 * Return: %true if at least one page exists in the specified range,478 * %false otherwise.479 */480bool filemap_range_has_page(struct address_space *mapping,481 loff_t start_byte, loff_t end_byte)482{483 struct folio *folio;484 XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT);485 pgoff_t max = end_byte >> PAGE_SHIFT;486 487 if (end_byte < start_byte)488 return false;489 490 rcu_read_lock();491 for (;;) {492 folio = xas_find(&xas, max);493 if (xas_retry(&xas, folio))494 continue;495 /* Shadow entries don't count */496 if (xa_is_value(folio))497 continue;498 /*499 * We don't need to try to pin this page; we're about to500 * release the RCU lock anyway. It is enough to know that501 * there was a page here recently.502 */503 break;504 }505 rcu_read_unlock();506 507 return folio != NULL;508}509EXPORT_SYMBOL(filemap_range_has_page);510 511static HWJS_SUSPENDS void __filemap_fdatawait_range(struct address_space *mapping,512 loff_t start_byte, loff_t end_byte)513{514 pgoff_t index = start_byte >> PAGE_SHIFT;515 pgoff_t end = end_byte >> PAGE_SHIFT;516 struct folio_batch fbatch;517 unsigned nr_folios;518 519 folio_batch_init(&fbatch);520 521 while (index <= end) {522 unsigned i;523 524 nr_folios = filemap_get_folios_tag(mapping, &index, end,525 PAGECACHE_TAG_WRITEBACK, &fbatch);526 527 if (!nr_folios)528 break;529 530 for (i = 0; i < nr_folios; i++) {531 struct folio *folio = fbatch.folios[i];532 533 folio_wait_writeback(folio);534 }535 folio_batch_release(&fbatch);536 cond_resched();537 }538}539 540/**541 * filemap_fdatawait_range - wait for writeback to complete542 * @mapping: address space structure to wait for543 * @start_byte: offset in bytes where the range starts544 * @end_byte: offset in bytes where the range ends (inclusive)545 *546 * Walk the list of under-writeback pages of the given address space547 * in the given range and wait for all of them. Check error status of548 * the address space and return it.549 *550 * Since the error status of the address space is cleared by this function,551 * callers are responsible for checking the return value and handling and/or552 * reporting the error.553 *554 * Return: error status of the address space.555 */556int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,557 loff_t end_byte)558{559 __filemap_fdatawait_range(mapping, start_byte, end_byte);560 return filemap_check_errors(mapping);561}562EXPORT_SYMBOL(filemap_fdatawait_range);563 564/**565 * filemap_fdatawait_range_keep_errors - wait for writeback to complete566 * @mapping: address space structure to wait for567 * @start_byte: offset in bytes where the range starts568 * @end_byte: offset in bytes where the range ends (inclusive)569 *570 * Walk the list of under-writeback pages of the given address space in the571 * given range and wait for all of them. Unlike filemap_fdatawait_range(),572 * this function does not clear error status of the address space.573 *574 * Use this function if callers don't handle errors themselves. Expected575 * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2),576 * fsfreeze(8)577 */578int filemap_fdatawait_range_keep_errors(struct address_space *mapping,579 loff_t start_byte, loff_t end_byte)580{581 __filemap_fdatawait_range(mapping, start_byte, end_byte);582 return filemap_check_and_keep_errors(mapping);583}584EXPORT_SYMBOL(filemap_fdatawait_range_keep_errors);585 586/**587 * file_fdatawait_range - wait for writeback to complete588 * @file: file pointing to address space structure to wait for589 * @start_byte: offset in bytes where the range starts590 * @end_byte: offset in bytes where the range ends (inclusive)591 *592 * Walk the list of under-writeback pages of the address space that file593 * refers to, in the given range and wait for all of them. Check error594 * status of the address space vs. the file->f_wb_err cursor and return it.595 *596 * Since the error status of the file is advanced by this function,597 * callers are responsible for checking the return value and handling and/or598 * reporting the error.599 *600 * Return: error status of the address space vs. the file->f_wb_err cursor.601 */602int file_fdatawait_range(struct file *file, loff_t start_byte, loff_t end_byte)603{604 struct address_space *mapping = file->f_mapping;605 606 __filemap_fdatawait_range(mapping, start_byte, end_byte);607 return file_check_and_advance_wb_err(file);608}609EXPORT_SYMBOL(file_fdatawait_range);610 611/**612 * filemap_fdatawait_keep_errors - wait for writeback without clearing errors613 * @mapping: address space structure to wait for614 *615 * Walk the list of under-writeback pages of the given address space616 * and wait for all of them. Unlike filemap_fdatawait(), this function617 * does not clear error status of the address space.618 *619 * Use this function if callers don't handle errors themselves. Expected620 * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2),621 * fsfreeze(8)622 *623 * Return: error status of the address space.624 */625int filemap_fdatawait_keep_errors(struct address_space *mapping)626{627 __filemap_fdatawait_range(mapping, 0, LLONG_MAX);628 return filemap_check_and_keep_errors(mapping);629}630EXPORT_SYMBOL(filemap_fdatawait_keep_errors);631 632/* Returns true if writeback might be needed or already in progress. */633static bool mapping_needs_writeback(struct address_space *mapping)634{635 return mapping->nrpages;636}637 638bool filemap_range_has_writeback(struct address_space *mapping,639 loff_t start_byte, loff_t end_byte)640{641 XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT);642 pgoff_t max = end_byte >> PAGE_SHIFT;643 struct folio *folio;644 645 if (end_byte < start_byte)646 return false;647 648 rcu_read_lock();649 xas_for_each(&xas, folio, max) {650 if (xas_retry(&xas, folio))651 continue;652 if (xa_is_value(folio))653 continue;654 if (folio_test_dirty(folio) || folio_test_locked(folio) ||655 folio_test_writeback(folio))656 break;657 }658 rcu_read_unlock();659 return folio != NULL;660}661EXPORT_SYMBOL_GPL(filemap_range_has_writeback);662 663/**664 * filemap_write_and_wait_range - write out & wait on a file range665 * @mapping: the address_space for the pages666 * @lstart: offset in bytes where the range starts667 * @lend: offset in bytes where the range ends (inclusive)668 *669 * Write out and wait upon file offsets lstart->lend, inclusive.670 *671 * Note that @lend is inclusive (describes the last byte to be written) so672 * that this function can be used to write to the very end-of-file (end = -1).673 *674 * Return: error status of the address space.675 */676int filemap_write_and_wait_range(struct address_space *mapping,677 loff_t lstart, loff_t lend)678{679 int err = 0, err2;680 681 if (lend < lstart)682 return 0;683 684 if (mapping_needs_writeback(mapping)) {685 err = __filemap_fdatawrite_range(mapping, lstart, lend,686 WB_SYNC_ALL);687 /*688 * Even if the above returned error, the pages may be689 * written partially (e.g. -ENOSPC), so we wait for it.690 * But the -EIO is special case, it may indicate the worst691 * thing (e.g. bug) happened, so we avoid waiting for it.692 */693 if (err != -EIO)694 __filemap_fdatawait_range(mapping, lstart, lend);695 }696 err2 = filemap_check_errors(mapping);697 if (!err)698 err = err2;699 return err;700}701EXPORT_SYMBOL(filemap_write_and_wait_range);702 703void __filemap_set_wb_err(struct address_space *mapping, int err)704{705 errseq_t eseq = errseq_set(&mapping->wb_err, err);706 707 trace_filemap_set_wb_err(mapping, eseq);708}709EXPORT_SYMBOL(__filemap_set_wb_err);710 711/**712 * file_check_and_advance_wb_err - report wb error (if any) that was previously713 * and advance wb_err to current one714 * @file: struct file on which the error is being reported715 *716 * When userland calls fsync (or something like nfsd does the equivalent), we717 * want to report any writeback errors that occurred since the last fsync (or718 * since the file was opened if there haven't been any).719 *720 * Grab the wb_err from the mapping. If it matches what we have in the file,721 * then just quickly return 0. The file is all caught up.722 *723 * If it doesn't match, then take the mapping value, set the "seen" flag in724 * it and try to swap it into place. If it works, or another task beat us725 * to it with the new value, then update the f_wb_err and return the error726 * portion. The error at this point must be reported via proper channels727 * (a'la fsync, or NFS COMMIT operation, etc.).728 *729 * While we handle mapping->wb_err with atomic operations, the f_wb_err730 * value is protected by the f_lock since we must ensure that it reflects731 * the latest value swapped in for this file descriptor.732 *733 * Return: %0 on success, negative error code otherwise.734 */735int file_check_and_advance_wb_err(struct file *file)736{737 int err = 0;738 errseq_t old = READ_ONCE(file->f_wb_err);739 struct address_space *mapping = file->f_mapping;740 741 /* Locklessly handle the common case where nothing has changed */742 if (errseq_check(&mapping->wb_err, old)) {743 /* Something changed, must use slow path */744 spin_lock(&file->f_lock);745 old = file->f_wb_err;746 err = errseq_check_and_advance(&mapping->wb_err,747 &file->f_wb_err);748 trace_file_check_and_advance_wb_err(file, old);749 spin_unlock(&file->f_lock);750 }751 752 /*753 * We're mostly using this function as a drop in replacement for754 * filemap_check_errors. Clear AS_EIO/AS_ENOSPC to emulate the effect755 * that the legacy code would have had on these flags.756 */757 clear_bit(AS_EIO, &mapping->flags);758 clear_bit(AS_ENOSPC, &mapping->flags);759 return err;760}761EXPORT_SYMBOL(file_check_and_advance_wb_err);762 763/**764 * file_write_and_wait_range - write out & wait on a file range765 * @file: file pointing to address_space with pages766 * @lstart: offset in bytes where the range starts767 * @lend: offset in bytes where the range ends (inclusive)768 *769 * Write out and wait upon file offsets lstart->lend, inclusive.770 *771 * Note that @lend is inclusive (describes the last byte to be written) so772 * that this function can be used to write to the very end-of-file (end = -1).773 *774 * After writing out and waiting on the data, we check and advance the775 * f_wb_err cursor to the latest value, and return any errors detected there.776 *777 * Return: %0 on success, negative error code otherwise.778 */779int file_write_and_wait_range(struct file *file, loff_t lstart, loff_t lend)780{781 int err = 0, err2;782 struct address_space *mapping = file->f_mapping;783 784 if (lend < lstart)785 return 0;786 787 if (mapping_needs_writeback(mapping)) {788 err = __filemap_fdatawrite_range(mapping, lstart, lend,789 WB_SYNC_ALL);790 /* See comment of filemap_write_and_wait() */791 if (err != -EIO)792 __filemap_fdatawait_range(mapping, lstart, lend);793 }794 err2 = file_check_and_advance_wb_err(file);795 if (!err)796 err = err2;797 return err;798}799EXPORT_SYMBOL(file_write_and_wait_range);800 801/**802 * replace_page_cache_folio - replace a pagecache folio with a new one803 * @old: folio to be replaced804 * @new: folio to replace with805 *806 * This function replaces a folio in the pagecache with a new one. On807 * success it acquires the pagecache reference for the new folio and808 * drops it for the old folio. Both the old and new folios must be809 * locked. This function does not add the new folio to the LRU, the810 * caller must do that.811 *812 * The remove + add is atomic. This function cannot fail.813 */814void replace_page_cache_folio(struct folio *old, struct folio *new)815{816 struct address_space *mapping = old->mapping;817 void (*free_folio)(struct folio *) = mapping->a_ops->free_folio;818 pgoff_t offset = old->index;819 XA_STATE(xas, &mapping->i_pages, offset);820 821 VM_BUG_ON_FOLIO(!folio_test_locked(old), old);822 VM_BUG_ON_FOLIO(!folio_test_locked(new), new);823 VM_BUG_ON_FOLIO(new->mapping, new);824 825 folio_get(new);826 new->mapping = mapping;827 new->index = offset;828 829 mem_cgroup_replace_folio(old, new);830 831 xas_lock_irq(&xas);832 xas_store(&xas, new);833 834 old->mapping = NULL;835 /* hugetlb pages do not participate in page cache accounting. */836 if (!folio_test_hugetlb(old))837 __lruvec_stat_sub_folio(old, NR_FILE_PAGES);838 if (!folio_test_hugetlb(new))839 __lruvec_stat_add_folio(new, NR_FILE_PAGES);840 if (folio_test_swapbacked(old))841 __lruvec_stat_sub_folio(old, NR_SHMEM);842 if (folio_test_swapbacked(new))843 __lruvec_stat_add_folio(new, NR_SHMEM);844 xas_unlock_irq(&xas);845 if (free_folio)846 free_folio(old);847 folio_put(old);848}849EXPORT_SYMBOL_GPL(replace_page_cache_folio);850 851noinline int __filemap_add_folio(struct address_space *mapping,852 struct folio *folio, pgoff_t index, gfp_t gfp, void **shadowp)853{854 XA_STATE(xas, &mapping->i_pages, index);855 void *alloced_shadow = NULL;856 int alloced_order = 0;857 bool huge;858 long nr;859 860 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);861 VM_BUG_ON_FOLIO(folio_test_swapbacked(folio), folio);862 VM_BUG_ON_FOLIO(folio_order(folio) < mapping_min_folio_order(mapping),863 folio);864 mapping_set_update(&xas, mapping);865 866 VM_BUG_ON_FOLIO(index & (folio_nr_pages(folio) - 1), folio);867 xas_set_order(&xas, index, folio_order(folio));868 huge = folio_test_hugetlb(folio);869 nr = folio_nr_pages(folio);870 871 gfp &= GFP_RECLAIM_MASK;872 folio_ref_add(folio, nr);873 folio->mapping = mapping;874 folio->index = xas.xa_index;875 876 for (;;) {877 int order = -1, split_order = 0;878 void *entry, *old = NULL;879 880 xas_lock_irq(&xas);881 xas_for_each_conflict(&xas, entry) {882 old = entry;883 if (!xa_is_value(entry)) {884 xas_set_err(&xas, -EEXIST);885 goto unlock;886 }887 /*888 * If a larger entry exists,889 * it will be the first and only entry iterated.890 */891 if (order == -1)892 order = xas_get_order(&xas);893 }894 895 /* entry may have changed before we re-acquire the lock */896 if (alloced_order && (old != alloced_shadow || order != alloced_order)) {897 xas_destroy(&xas);898 alloced_order = 0;899 }900 901 if (old) {902 if (order > 0 && order > folio_order(folio)) {903 /* How to handle large swap entries? */904 BUG_ON(shmem_mapping(mapping));905 if (!alloced_order) {906 split_order = order;907 goto unlock;908 }909 xas_split(&xas, old, order);910 xas_reset(&xas);911 }912 if (shadowp)913 *shadowp = old;914 }915 916 xas_store(&xas, folio);917 if (xas_error(&xas))918 goto unlock;919 920 mapping->nrpages += nr;921 922 /* hugetlb pages do not participate in page cache accounting */923 if (!huge) {924 __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr);925 if (folio_test_pmd_mappable(folio))926 __lruvec_stat_mod_folio(folio,927 NR_FILE_THPS, nr);928 }929 930unlock:931 xas_unlock_irq(&xas);932 933 /* split needed, alloc here and retry. */934 if (split_order) {935 xas_split_alloc(&xas, old, split_order, gfp);936 if (xas_error(&xas))937 goto error;938 alloced_shadow = old;939 alloced_order = split_order;940 xas_reset(&xas);941 continue;942 }943 944 if (!xas_nomem(&xas, gfp))945 break;946 }947 948 if (xas_error(&xas))949 goto error;950 951 trace_mm_filemap_add_to_page_cache(folio);952 return 0;953error:954 folio->mapping = NULL;955 /* Leave page->index set: truncation relies upon it */956 folio_put_refs(folio, nr);957 return xas_error(&xas);958}959ALLOW_ERROR_INJECTION(__filemap_add_folio, ERRNO);960 961int filemap_add_folio(struct address_space *mapping, struct folio *folio,962 pgoff_t index, gfp_t gfp)963{964 void *shadow = NULL;965 int ret;966 967 ret = mem_cgroup_charge(folio, NULL, gfp);968 if (ret)969 return ret;970 971 __folio_set_locked(folio);972 ret = __filemap_add_folio(mapping, folio, index, gfp, &shadow);973 if (unlikely(ret)) {974 mem_cgroup_uncharge(folio);975 __folio_clear_locked(folio);976 } else {977 /*978 * The folio might have been evicted from cache only979 * recently, in which case it should be activated like980 * any other repeatedly accessed folio.981 * The exception is folios getting rewritten; evicting other982 * data from the working set, only to cache data that will983 * get overwritten with something else, is a waste of memory.984 */985 WARN_ON_ONCE(folio_test_active(folio));986 if (!(gfp & __GFP_WRITE) && shadow)987 workingset_refault(folio, shadow);988 folio_add_lru(folio);989 }990 return ret;991}992EXPORT_SYMBOL_GPL(filemap_add_folio);993 994#ifdef CONFIG_NUMA995struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order)996{997 int n;998 struct folio *folio;999 1000 if (cpuset_do_page_mem_spread()) {1001 unsigned int cpuset_mems_cookie;1002 do {1003 cpuset_mems_cookie = read_mems_allowed_begin();1004 n = cpuset_mem_spread_node();1005 folio = __folio_alloc_node_noprof(gfp, order, n);1006 } while (!folio && read_mems_allowed_retry(cpuset_mems_cookie));1007 1008 return folio;1009 }1010 return folio_alloc_noprof(gfp, order);1011}1012EXPORT_SYMBOL(filemap_alloc_folio_noprof);1013#endif1014 1015/*1016 * filemap_invalidate_lock_two - lock invalidate_lock for two mappings1017 *1018 * Lock exclusively invalidate_lock of any passed mapping that is not NULL.1019 *1020 * @mapping1: the first mapping to lock1021 * @mapping2: the second mapping to lock1022 */1023void filemap_invalidate_lock_two(struct address_space *mapping1,1024 struct address_space *mapping2)1025{1026 if (mapping1 > mapping2)1027 swap(mapping1, mapping2);1028 if (mapping1)1029 down_write(&mapping1->invalidate_lock);1030 if (mapping2 && mapping1 != mapping2)1031 down_write_nested(&mapping2->invalidate_lock, 1);1032}1033EXPORT_SYMBOL(filemap_invalidate_lock_two);1034 1035/*1036 * filemap_invalidate_unlock_two - unlock invalidate_lock for two mappings1037 *1038 * Unlock exclusive invalidate_lock of any passed mapping that is not NULL.1039 *1040 * @mapping1: the first mapping to unlock1041 * @mapping2: the second mapping to unlock1042 */1043void filemap_invalidate_unlock_two(struct address_space *mapping1,1044 struct address_space *mapping2)1045{1046 if (mapping1)1047 up_write(&mapping1->invalidate_lock);1048 if (mapping2 && mapping1 != mapping2)1049 up_write(&mapping2->invalidate_lock);1050}1051EXPORT_SYMBOL(filemap_invalidate_unlock_two);1052 1053/*1054 * In order to wait for pages to become available there must be1055 * waitqueues associated with pages. By using a hash table of1056 * waitqueues where the bucket discipline is to maintain all1057 * waiters on the same queue and wake all when any of the pages1058 * become available, and for the woken contexts to check to be1059 * sure the appropriate page became available, this saves space1060 * at a cost of "thundering herd" phenomena during rare hash1061 * collisions.1062 */1063#define PAGE_WAIT_TABLE_BITS 81064#define PAGE_WAIT_TABLE_SIZE (1 << PAGE_WAIT_TABLE_BITS)1065static wait_queue_head_t folio_wait_table[PAGE_WAIT_TABLE_SIZE] __cacheline_aligned;1066 1067static wait_queue_head_t *folio_waitqueue(struct folio *folio)1068{1069 return &folio_wait_table[hash_ptr(folio, PAGE_WAIT_TABLE_BITS)];1070}1071 1072void __init pagecache_init(void)1073{1074 int i;1075 1076 for (i = 0; i < PAGE_WAIT_TABLE_SIZE; i++)1077 init_waitqueue_head(&folio_wait_table[i]);1078 1079 page_writeback_init();1080}1081 1082/*1083 * The page wait code treats the "wait->flags" somewhat unusually, because1084 * we have multiple different kinds of waits, not just the usual "exclusive"1085 * one.1086 *1087 * We have:1088 *1089 * (a) no special bits set:1090 *1091 * We're just waiting for the bit to be released, and when a waker1092 * calls the wakeup function, we set WQ_FLAG_WOKEN and wake it up,1093 * and remove it from the wait queue.1094 *1095 * Simple and straightforward.1096 *1097 * (b) WQ_FLAG_EXCLUSIVE:1098 *1099 * The waiter is waiting to get the lock, and only one waiter should1100 * be woken up to avoid any thundering herd behavior. We'll set the1101 * WQ_FLAG_WOKEN bit, wake it up, and remove it from the wait queue.1102 *1103 * This is the traditional exclusive wait.1104 *1105 * (c) WQ_FLAG_EXCLUSIVE | WQ_FLAG_CUSTOM:1106 *1107 * The waiter is waiting to get the bit, and additionally wants the1108 * lock to be transferred to it for fair lock behavior. If the lock1109 * cannot be taken, we stop walking the wait queue without waking1110 * the waiter.1111 *1112 * This is the "fair lock handoff" case, and in addition to setting1113 * WQ_FLAG_WOKEN, we set WQ_FLAG_DONE to let the waiter easily see1114 * that it now has the lock.1115 */1116static HWJS_SUSPENDS int wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *arg)1117{1118 unsigned int flags;1119 struct wait_page_key *key = arg;1120 struct wait_page_queue *wait_page1121 = container_of(wait, struct wait_page_queue, wait);1122 1123 if (!wake_page_match(wait_page, key))1124 return 0;1125 1126 /*1127 * If it's a lock handoff wait, we get the bit for it, and1128 * stop walking (and do not wake it up) if we can't.1129 */1130 flags = wait->flags;1131 if (flags & WQ_FLAG_EXCLUSIVE) {1132 if (test_bit(key->bit_nr, &key->folio->flags))1133 return -1;1134 if (flags & WQ_FLAG_CUSTOM) {1135 if (test_and_set_bit(key->bit_nr, &key->folio->flags))1136 return -1;1137 flags |= WQ_FLAG_DONE;1138 }1139 }1140 1141 /*1142 * We are holding the wait-queue lock, but the waiter that1143 * is waiting for this will be checking the flags without1144 * any locking.1145 *1146 * So update the flags atomically, and wake up the waiter1147 * afterwards to avoid any races. This store-release pairs1148 * with the load-acquire in folio_wait_bit_common().1149 */1150 smp_store_release(&wait->flags, flags | WQ_FLAG_WOKEN);1151 wake_up_state(wait->private, mode);1152 1153 /*1154 * Ok, we have successfully done what we're waiting for,1155 * and we can unconditionally remove the wait entry.1156 *1157 * Note that this pairs with the "finish_wait()" in the1158 * waiter, and has to be the absolute last thing we do.1159 * After this list_del_init(&wait->entry) the wait entry1160 * might be de-allocated and the process might even have1161 * exited.1162 */1163 list_del_init_careful(&wait->entry);1164 return (flags & WQ_FLAG_EXCLUSIVE) != 0;1165}1166 1167static HWJS_SUSPENDS void folio_wake_bit(struct folio *folio, int bit_nr)1168{1169 wait_queue_head_t *q = folio_waitqueue(folio);1170 struct wait_page_key key;1171 unsigned long flags;1172 1173 key.folio = folio;1174 key.bit_nr = bit_nr;1175 key.page_match = 0;1176 1177 spin_lock_irqsave(&q->lock, flags);1178 __wake_up_locked_key(q, TASK_NORMAL, &key);1179 1180 /*1181 * It's possible to miss clearing waiters here, when we woke our page1182 * waiters, but the hashed waitqueue has waiters for other pages on it.1183 * That's okay, it's a rare case. The next waker will clear it.1184 *1185 * Note that, depending on the page pool (buddy, hugetlb, ZONE_DEVICE,1186 * other), the flag may be cleared in the course of freeing the page;1187 * but that is not required for correctness.1188 */1189 if (!waitqueue_active(q) || !key.page_match)1190 folio_clear_waiters(folio);1191 1192 spin_unlock_irqrestore(&q->lock, flags);1193}1194 1195/*1196 * A choice of three behaviors for folio_wait_bit_common():1197 */1198enum behavior {1199 EXCLUSIVE, /* Hold ref to page and take the bit when woken, like1200 * __folio_lock() waiting on then setting PG_locked.1201 */1202 SHARED, /* Hold ref to page and check the bit when woken, like1203 * folio_wait_writeback() waiting on PG_writeback.1204 */1205 DROP, /* Drop ref to page before wait, no check when woken,1206 * like folio_put_wait_locked() on PG_locked.1207 */1208};1209 1210/*1211 * Attempt to check (or get) the folio flag, and mark us done1212 * if successful.1213 */1214static inline bool folio_trylock_flag(struct folio *folio, int bit_nr,1215 struct wait_queue_entry *wait)1216{1217 if (wait->flags & WQ_FLAG_EXCLUSIVE) {1218 if (test_and_set_bit(bit_nr, &folio->flags))1219 return false;1220 } else if (test_bit(bit_nr, &folio->flags))1221 return false;1222 1223 wait->flags |= WQ_FLAG_WOKEN | WQ_FLAG_DONE;1224 return true;1225}1226 1227/* How many times do we accept lock stealing from under a waiter? */1228int sysctl_page_lock_unfairness = 5;1229 1230static HWJS_SUSPENDS inline int folio_wait_bit_common(struct folio *folio, int bit_nr,1231 int state, enum behavior behavior)1232{1233 wait_queue_head_t *q = folio_waitqueue(folio);1234 int unfairness = sysctl_page_lock_unfairness;1235 struct wait_page_queue wait_page;1236 wait_queue_entry_t *wait = &wait_page.wait;1237 bool thrashing = false;1238 unsigned long pflags;1239 bool in_thrashing;1240 1241 if (bit_nr == PG_locked &&1242 !folio_test_uptodate(folio) && folio_test_workingset(folio)) {1243 delayacct_thrashing_start(&in_thrashing);1244 psi_memstall_enter(&pflags);1245 thrashing = true;1246 }1247 1248 init_wait(wait);1249 wait->func = wake_page_function;1250 wait_page.folio = folio;1251 wait_page.bit_nr = bit_nr;1252 1253repeat:1254 wait->flags = 0;1255 if (behavior == EXCLUSIVE) {1256 wait->flags = WQ_FLAG_EXCLUSIVE;1257 if (--unfairness < 0)1258 wait->flags |= WQ_FLAG_CUSTOM;1259 }1260 1261 /*1262 * Do one last check whether we can get the1263 * page bit synchronously.1264 *1265 * Do the folio_set_waiters() marking before that1266 * to let any waker we _just_ missed know they1267 * need to wake us up (otherwise they'll never1268 * even go to the slow case that looks at the1269 * page queue), and add ourselves to the wait1270 * queue if we need to sleep.1271 *1272 * This part needs to be done under the queue1273 * lock to avoid races.1274 */1275 spin_lock_irq(&q->lock);1276 folio_set_waiters(folio);1277 if (!folio_trylock_flag(folio, bit_nr, wait))1278 __add_wait_queue_entry_tail(q, wait);1279 spin_unlock_irq(&q->lock);1280 1281 /*1282 * From now on, all the logic will be based on1283 * the WQ_FLAG_WOKEN and WQ_FLAG_DONE flag, to1284 * see whether the page bit testing has already1285 * been done by the wake function.1286 *1287 * We can drop our reference to the folio.1288 */1289 if (behavior == DROP)1290 folio_put(folio);1291 1292 /*1293 * Note that until the "finish_wait()", or until1294 * we see the WQ_FLAG_WOKEN flag, we need to1295 * be very careful with the 'wait->flags', because1296 * we may race with a waker that sets them.1297 */1298 for (;;) {1299 unsigned int flags;1300 1301 set_current_state(state);1302 1303 /* Loop until we've been woken or interrupted */1304 flags = smp_load_acquire(&wait->flags);1305 if (!(flags & WQ_FLAG_WOKEN)) {1306 if (signal_pending_state(state, current))1307 break;1308 1309 io_schedule();1310 continue;1311 }1312 1313 /* If we were non-exclusive, we're done */1314 if (behavior != EXCLUSIVE)1315 break;1316 1317 /* If the waker got the lock for us, we're done */1318 if (flags & WQ_FLAG_DONE)1319 break;1320 1321 /*1322 * Otherwise, if we're getting the lock, we need to1323 * try to get it ourselves.1324 *1325 * And if that fails, we'll have to retry this all.1326 */1327 if (unlikely(test_and_set_bit(bit_nr, folio_flags(folio, 0))))1328 goto repeat;1329 1330 wait->flags |= WQ_FLAG_DONE;1331 break;1332 }1333 1334 /*1335 * If a signal happened, this 'finish_wait()' may remove the last1336 * waiter from the wait-queues, but the folio waiters bit will remain1337 * set. That's ok. The next wakeup will take care of it, and trying1338 * to do it here would be difficult and prone to races.1339 */1340 finish_wait(q, wait);1341 1342 if (thrashing) {1343 delayacct_thrashing_end(&in_thrashing);1344 psi_memstall_leave(&pflags);1345 }1346 1347 /*1348 * NOTE! The wait->flags weren't stable until we've done the1349 * 'finish_wait()', and we could have exited the loop above due1350 * to a signal, and had a wakeup event happen after the signal1351 * test but before the 'finish_wait()'.1352 *1353 * So only after the finish_wait() can we reliably determine1354 * if we got woken up or not, so we can now figure out the final1355 * return value based on that state without races.1356 *1357 * Also note that WQ_FLAG_WOKEN is sufficient for a non-exclusive1358 * waiter, but an exclusive one requires WQ_FLAG_DONE.1359 */1360 if (behavior == EXCLUSIVE)1361 return wait->flags & WQ_FLAG_DONE ? 0 : -EINTR;1362 1363 return wait->flags & WQ_FLAG_WOKEN ? 0 : -EINTR;1364}1365 1366#ifdef CONFIG_MIGRATION1367/**1368 * migration_entry_wait_on_locked - Wait for a migration entry to be removed1369 * @entry: migration swap entry.1370 * @ptl: already locked ptl. This function will drop the lock.1371 *1372 * Wait for a migration entry referencing the given page to be removed. This is1373 * equivalent to put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE) except1374 * this can be called without taking a reference on the page. Instead this1375 * should be called while holding the ptl for the migration entry referencing1376 * the page.1377 *1378 * Returns after unlocking the ptl.1379 *1380 * This follows the same logic as folio_wait_bit_common() so see the comments1381 * there.1382 */1383void migration_entry_wait_on_locked(swp_entry_t entry, spinlock_t *ptl)1384 __releases(ptl)1385{1386 struct wait_page_queue wait_page;1387 wait_queue_entry_t *wait = &wait_page.wait;1388 bool thrashing = false;1389 unsigned long pflags;1390 bool in_thrashing;1391 wait_queue_head_t *q;1392 struct folio *folio = pfn_swap_entry_folio(entry);1393 1394 q = folio_waitqueue(folio);1395 if (!folio_test_uptodate(folio) && folio_test_workingset(folio)) {1396 delayacct_thrashing_start(&in_thrashing);1397 psi_memstall_enter(&pflags);1398 thrashing = true;1399 }1400 1401 init_wait(wait);1402 wait->func = wake_page_function;1403 wait_page.folio = folio;1404 wait_page.bit_nr = PG_locked;1405 wait->flags = 0;1406 1407 spin_lock_irq(&q->lock);1408 folio_set_waiters(folio);1409 if (!folio_trylock_flag(folio, PG_locked, wait))1410 __add_wait_queue_entry_tail(q, wait);1411 spin_unlock_irq(&q->lock);1412 1413 /*1414 * If a migration entry exists for the page the migration path must hold1415 * a valid reference to the page, and it must take the ptl to remove the1416 * migration entry. So the page is valid until the ptl is dropped.1417 */1418 spin_unlock(ptl);1419 1420 for (;;) {1421 unsigned int flags;1422 1423 set_current_state(TASK_UNINTERRUPTIBLE);1424 1425 /* Loop until we've been woken or interrupted */1426 flags = smp_load_acquire(&wait->flags);1427 if (!(flags & WQ_FLAG_WOKEN)) {1428 if (signal_pending_state(TASK_UNINTERRUPTIBLE, current))1429 break;1430 1431 io_schedule();1432 continue;1433 }1434 break;1435 }1436 1437 finish_wait(q, wait);1438 1439 if (thrashing) {1440 delayacct_thrashing_end(&in_thrashing);1441 psi_memstall_leave(&pflags);1442 }1443}1444#endif1445 1446void folio_wait_bit(struct folio *folio, int bit_nr)1447{1448 folio_wait_bit_common(folio, bit_nr, TASK_UNINTERRUPTIBLE, SHARED);1449}1450EXPORT_SYMBOL(folio_wait_bit);1451 1452int folio_wait_bit_killable(struct folio *folio, int bit_nr)1453{1454 return folio_wait_bit_common(folio, bit_nr, TASK_KILLABLE, SHARED);1455}1456EXPORT_SYMBOL(folio_wait_bit_killable);1457 1458/**1459 * folio_put_wait_locked - Drop a reference and wait for it to be unlocked1460 * @folio: The folio to wait for.1461 * @state: The sleep state (TASK_KILLABLE, TASK_UNINTERRUPTIBLE, etc).1462 *1463 * The caller should hold a reference on @folio. They expect the page to1464 * become unlocked relatively soon, but do not wish to hold up migration1465 * (for example) by holding the reference while waiting for the folio to1466 * come unlocked. After this function returns, the caller should not1467 * dereference @folio.1468 *1469 * Return: 0 if the folio was unlocked or -EINTR if interrupted by a signal.1470 */1471static HWJS_SUSPENDS int folio_put_wait_locked(struct folio *folio, int state)1472{1473 return folio_wait_bit_common(folio, PG_locked, state, DROP);1474}1475 1476/**1477 * folio_add_wait_queue - Add an arbitrary waiter to a folio's wait queue1478 * @folio: Folio defining the wait queue of interest1479 * @waiter: Waiter to add to the queue1480 *1481 * Add an arbitrary @waiter to the wait queue for the nominated @folio.1482 */1483void folio_add_wait_queue(struct folio *folio, wait_queue_entry_t *waiter)1484{1485 wait_queue_head_t *q = folio_waitqueue(folio);1486 unsigned long flags;1487 1488 spin_lock_irqsave(&q->lock, flags);1489 __add_wait_queue_entry_tail(q, waiter);1490 folio_set_waiters(folio);1491 spin_unlock_irqrestore(&q->lock, flags);1492}1493EXPORT_SYMBOL_GPL(folio_add_wait_queue);1494 1495/**1496 * folio_unlock - Unlock a locked folio.1497 * @folio: The folio.1498 *1499 * Unlocks the folio and wakes up any thread sleeping on the page lock.1500 *1501 * Context: May be called from interrupt or process context. May not be1502 * called from NMI context.1503 */1504void folio_unlock(struct folio *folio)1505{1506 /* Bit 7 allows x86 to check the byte's sign bit */1507 BUILD_BUG_ON(PG_waiters != 7);1508 BUILD_BUG_ON(PG_locked > 7);1509 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);1510 if (folio_xor_flags_has_waiters(folio, 1 << PG_locked))1511 folio_wake_bit(folio, PG_locked);1512}1513EXPORT_SYMBOL(folio_unlock);1514 1515/**1516 * folio_end_read - End read on a folio.1517 * @folio: The folio.1518 * @success: True if all reads completed successfully.1519 *1520 * When all reads against a folio have completed, filesystems should1521 * call this function to let the pagecache know that no more reads1522 * are outstanding. This will unlock the folio and wake up any thread1523 * sleeping on the lock. The folio will also be marked uptodate if all1524 * reads succeeded.1525 *1526 * Context: May be called from interrupt or process context. May not be1527 * called from NMI context.1528 */1529void folio_end_read(struct folio *folio, bool success)1530{1531 unsigned long mask = 1 << PG_locked;1532 1533 /* Must be in bottom byte for x86 to work */1534 BUILD_BUG_ON(PG_uptodate > 7);1535 VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);1536 VM_BUG_ON_FOLIO(folio_test_uptodate(folio), folio);1537 1538 if (likely(success))1539 mask |= 1 << PG_uptodate;1540 if (folio_xor_flags_has_waiters(folio, mask))1541 folio_wake_bit(folio, PG_locked);1542}1543EXPORT_SYMBOL(folio_end_read);1544 1545/**1546 * folio_end_private_2 - Clear PG_private_2 and wake any waiters.1547 * @folio: The folio.1548 *1549 * Clear the PG_private_2 bit on a folio and wake up any sleepers waiting for1550 * it. The folio reference held for PG_private_2 being set is released.1551 *1552 * This is, for example, used when a netfs folio is being written to a local1553 * disk cache, thereby allowing writes to the cache for the same folio to be1554 * serialised.1555 */1556void folio_end_private_2(struct folio *folio)1557{1558 VM_BUG_ON_FOLIO(!folio_test_private_2(folio), folio);1559 clear_bit_unlock(PG_private_2, folio_flags(folio, 0));1560 folio_wake_bit(folio, PG_private_2);1561 folio_put(folio);1562}1563EXPORT_SYMBOL(folio_end_private_2);1564 1565/**1566 * folio_wait_private_2 - Wait for PG_private_2 to be cleared on a folio.1567 * @folio: The folio to wait on.1568 *1569 * Wait for PG_private_2 to be cleared on a folio.1570 */1571void folio_wait_private_2(struct folio *folio)1572{1573 while (folio_test_private_2(folio))1574 folio_wait_bit(folio, PG_private_2);1575}1576EXPORT_SYMBOL(folio_wait_private_2);1577 1578/**1579 * folio_wait_private_2_killable - Wait for PG_private_2 to be cleared on a folio.1580 * @folio: The folio to wait on.1581 *1582 * Wait for PG_private_2 to be cleared on a folio or until a fatal signal is1583 * received by the calling task.1584 *1585 * Return:1586 * - 0 if successful.1587 * - -EINTR if a fatal signal was encountered.1588 */1589int folio_wait_private_2_killable(struct folio *folio)1590{1591 int ret = 0;1592 1593 while (folio_test_private_2(folio)) {1594 ret = folio_wait_bit_killable(folio, PG_private_2);1595 if (ret < 0)1596 break;1597 }1598 1599 return ret;1600}1601EXPORT_SYMBOL(folio_wait_private_2_killable);1602 1603/**1604 * folio_end_writeback - End writeback against a folio.1605 * @folio: The folio.1606 *1607 * The folio must actually be under writeback.1608 *1609 * Context: May be called from process or interrupt context.1610 */1611void folio_end_writeback(struct folio *folio)1612{1613 VM_BUG_ON_FOLIO(!folio_test_writeback(folio), folio);1614 1615 /*1616 * folio_test_clear_reclaim() could be used here but it is an1617 * atomic operation and overkill in this particular case. Failing1618 * to shuffle a folio marked for immediate reclaim is too mild1619 * a gain to justify taking an atomic operation penalty at the1620 * end of every folio writeback.1621 */1622 if (folio_test_reclaim(folio)) {1623 folio_clear_reclaim(folio);1624 folio_rotate_reclaimable(folio);1625 }1626 1627 /*1628 * Writeback does not hold a folio reference of its own, relying1629 * on truncation to wait for the clearing of PG_writeback.1630 * But here we must make sure that the folio is not freed and1631 * reused before the folio_wake_bit().1632 */1633 folio_get(folio);1634 if (__folio_end_writeback(folio))1635 folio_wake_bit(folio, PG_writeback);1636 acct_reclaim_writeback(folio);1637 folio_put(folio);1638}1639EXPORT_SYMBOL(folio_end_writeback);1640 1641/**1642 * __folio_lock - Get a lock on the folio, assuming we need to sleep to get it.1643 * @folio: The folio to lock1644 */1645void __folio_lock(struct folio *folio)1646{1647 folio_wait_bit_common(folio, PG_locked, TASK_UNINTERRUPTIBLE,1648 EXCLUSIVE);1649}1650EXPORT_SYMBOL(__folio_lock);1651 1652int __folio_lock_killable(struct folio *folio)1653{1654 return folio_wait_bit_common(folio, PG_locked, TASK_KILLABLE,1655 EXCLUSIVE);1656}1657EXPORT_SYMBOL_GPL(__folio_lock_killable);1658 1659static int __folio_lock_async(struct folio *folio, struct wait_page_queue *wait)1660{1661 struct wait_queue_head *q = folio_waitqueue(folio);1662 int ret;1663 1664 wait->folio = folio;1665 wait->bit_nr = PG_locked;1666 1667 spin_lock_irq(&q->lock);1668 __add_wait_queue_entry_tail(q, &wait->wait);1669 folio_set_waiters(folio);1670 ret = !folio_trylock(folio);1671 /*1672 * If we were successful now, we know we're still on the1673 * waitqueue as we're still under the lock. This means it's1674 * safe to remove and return success, we know the callback1675 * isn't going to trigger.1676 */1677 if (!ret)1678 __remove_wait_queue(q, &wait->wait);1679 else1680 ret = -EIOCBQUEUED;1681 spin_unlock_irq(&q->lock);1682 return ret;1683}1684 1685/*1686 * Return values:1687 * 0 - folio is locked.1688 * non-zero - folio is not locked.1689 * mmap_lock or per-VMA lock has been released (mmap_read_unlock() or1690 * vma_end_read()), unless flags had both FAULT_FLAG_ALLOW_RETRY and1691 * FAULT_FLAG_RETRY_NOWAIT set, in which case the lock is still held.1692 *1693 * If neither ALLOW_RETRY nor KILLABLE are set, will always return 01694 * with the folio locked and the mmap_lock/per-VMA lock is left unperturbed.1695 */1696vm_fault_t __folio_lock_or_retry(struct folio *folio, struct vm_fault *vmf)1697{1698 unsigned int flags = vmf->flags;1699 1700 if (fault_flag_allow_retry_first(flags)) {1701 /*1702 * CAUTION! In this case, mmap_lock/per-VMA lock is not1703 * released even though returning VM_FAULT_RETRY.1704 */1705 if (flags & FAULT_FLAG_RETRY_NOWAIT)1706 return VM_FAULT_RETRY;1707 1708 release_fault_lock(vmf);1709 if (flags & FAULT_FLAG_KILLABLE)1710 folio_wait_locked_killable(folio);1711 else1712 folio_wait_locked(folio);1713 return VM_FAULT_RETRY;1714 }1715 if (flags & FAULT_FLAG_KILLABLE) {1716 bool ret;1717 1718 ret = __folio_lock_killable(folio);1719 if (ret) {1720 release_fault_lock(vmf);1721 return VM_FAULT_RETRY;1722 }1723 } else {1724 __folio_lock(folio);1725 }1726 1727 return 0;1728}1729 1730/**1731 * page_cache_next_miss() - Find the next gap in the page cache.1732 * @mapping: Mapping.1733 * @index: Index.1734 * @max_scan: Maximum range to search.1735 *1736 * Search the range [index, min(index + max_scan - 1, ULONG_MAX)] for the1737 * gap with the lowest index.1738 *1739 * This function may be called under the rcu_read_lock. However, this will1740 * not atomically search a snapshot of the cache at a single point in time.1741 * For example, if a gap is created at index 5, then subsequently a gap is1742 * created at index 10, page_cache_next_miss covering both indices may1743 * return 10 if called under the rcu_read_lock.1744 *1745 * Return: The index of the gap if found, otherwise an index outside the1746 * range specified (in which case 'return - index >= max_scan' will be true).1747 * In the rare case of index wrap-around, 0 will be returned.1748 */1749pgoff_t page_cache_next_miss(struct address_space *mapping,1750 pgoff_t index, unsigned long max_scan)1751{1752 XA_STATE(xas, &mapping->i_pages, index);1753 1754 while (max_scan--) {1755 void *entry = xas_next(&xas);1756 if (!entry || xa_is_value(entry))1757 return xas.xa_index;1758 if (xas.xa_index == 0)1759 return 0;1760 }1761 1762 return index + max_scan;1763}1764EXPORT_SYMBOL(page_cache_next_miss);1765 1766/**1767 * page_cache_prev_miss() - Find the previous gap in the page cache.1768 * @mapping: Mapping.1769 * @index: Index.1770 * @max_scan: Maximum range to search.1771 *1772 * Search the range [max(index - max_scan + 1, 0), index] for the1773 * gap with the highest index.1774 *1775 * This function may be called under the rcu_read_lock. However, this will1776 * not atomically search a snapshot of the cache at a single point in time.1777 * For example, if a gap is created at index 10, then subsequently a gap is1778 * created at index 5, page_cache_prev_miss() covering both indices may1779 * return 5 if called under the rcu_read_lock.1780 *1781 * Return: The index of the gap if found, otherwise an index outside the1782 * range specified (in which case 'index - return >= max_scan' will be true).1783 * In the rare case of wrap-around, ULONG_MAX will be returned.1784 */1785pgoff_t page_cache_prev_miss(struct address_space *mapping,1786 pgoff_t index, unsigned long max_scan)1787{1788 XA_STATE(xas, &mapping->i_pages, index);1789 1790 while (max_scan--) {1791 void *entry = xas_prev(&xas);1792 if (!entry || xa_is_value(entry))1793 break;1794 if (xas.xa_index == ULONG_MAX)1795 break;1796 }1797 1798 return xas.xa_index;1799}1800EXPORT_SYMBOL(page_cache_prev_miss);1801 1802/*1803 * Lockless page cache protocol:1804 * On the lookup side:1805 * 1. Load the folio from i_pages1806 * 2. Increment the refcount if it's not zero1807 * 3. If the folio is not found by xas_reload(), put the refcount and retry1808 *1809 * On the removal side:1810 * A. Freeze the page (by zeroing the refcount if nobody else has a reference)1811 * B. Remove the page from i_pages1812 * C. Return the page to the page allocator1813 *1814 * This means that any page may have its reference count temporarily1815 * increased by a speculative page cache (or GUP-fast) lookup as it can1816 * be allocated by another user before the RCU grace period expires.1817 * Because the refcount temporarily acquired here may end up being the1818 * last refcount on the page, any page allocation must be freeable by1819 * folio_put().1820 */1821 1822/*1823 * filemap_get_entry - Get a page cache entry.1824 * @mapping: the address_space to search1825 * @index: The page cache index.1826 *1827 * Looks up the page cache entry at @mapping & @index. If it is a folio,1828 * it is returned with an increased refcount. If it is a shadow entry1829 * of a previously evicted folio, or a swap entry from shmem/tmpfs,1830 * it is returned without further action.1831 *1832 * Return: The folio, swap or shadow entry, %NULL if nothing is found.1833 */1834void *filemap_get_entry(struct address_space *mapping, pgoff_t index)1835{1836 XA_STATE(xas, &mapping->i_pages, index);1837 struct folio *folio;1838 1839 rcu_read_lock();1840repeat:1841 xas_reset(&xas);1842 folio = xas_load(&xas);1843 if (xas_retry(&xas, folio))1844 goto repeat;1845 /*1846 * A shadow entry of a recently evicted page, or a swap entry from1847 * shmem/tmpfs. Return it without attempting to raise page count.1848 */1849 if (!folio || xa_is_value(folio))1850 goto out;1851 1852 if (!folio_try_get(folio))1853 goto repeat;1854 1855 if (unlikely(folio != xas_reload(&xas))) {1856 folio_put(folio);1857 goto repeat;1858 }1859out:1860 rcu_read_unlock();1861 1862 return folio;1863}1864 1865/**1866 * __filemap_get_folio - Find and get a reference to a folio.1867 * @mapping: The address_space to search.1868 * @index: The page index.1869 * @fgp_flags: %FGP flags modify how the folio is returned.1870 * @gfp: Memory allocation flags to use if %FGP_CREAT is specified.1871 *1872 * Looks up the page cache entry at @mapping & @index.1873 *1874 * If %FGP_LOCK or %FGP_CREAT are specified then the function may sleep even1875 * if the %GFP flags specified for %FGP_CREAT are atomic.1876 *1877 * If this function returns a folio, it is returned with an increased refcount.1878 *1879 * Return: The found folio or an ERR_PTR() otherwise.1880 */1881struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,1882 fgf_t fgp_flags, gfp_t gfp)1883{1884 struct folio *folio;1885 1886repeat:1887 folio = filemap_get_entry(mapping, index);1888 if (xa_is_value(folio))1889 folio = NULL;1890 if (!folio)1891 goto no_page;1892 1893 if (fgp_flags & FGP_LOCK) {1894 if (fgp_flags & FGP_NOWAIT) {1895 if (!folio_trylock(folio)) {1896 folio_put(folio);1897 return ERR_PTR(-EAGAIN);1898 }1899 } else {1900 folio_lock(folio);1901 }1902 1903 /* Has the page been truncated? */1904 if (unlikely(folio->mapping != mapping)) {1905 folio_unlock(folio);1906 folio_put(folio);1907 goto repeat;1908 }1909 VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio);1910 }1911 1912 if (fgp_flags & FGP_ACCESSED)1913 folio_mark_accessed(folio);1914 else if (fgp_flags & FGP_WRITE) {1915 /* Clear idle flag for buffer write */1916 if (folio_test_idle(folio))1917 folio_clear_idle(folio);1918 }1919 1920 if (fgp_flags & FGP_STABLE)1921 folio_wait_stable(folio);1922no_page:1923 if (!folio && (fgp_flags & FGP_CREAT)) {1924 unsigned int min_order = mapping_min_folio_order(mapping);1925 unsigned int order = max(min_order, FGF_GET_ORDER(fgp_flags));1926 int err;1927 index = mapping_align_index(mapping, index);1928 1929 if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping))1930 gfp |= __GFP_WRITE;1931 if (fgp_flags & FGP_NOFS)1932 gfp &= ~__GFP_FS;1933 if (fgp_flags & FGP_NOWAIT) {1934 gfp &= ~GFP_KERNEL;1935 gfp |= GFP_NOWAIT | __GFP_NOWARN;1936 }1937 if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP))))1938 fgp_flags |= FGP_LOCK;1939 1940 if (order > mapping_max_folio_order(mapping))1941 order = mapping_max_folio_order(mapping);1942 /* If we're not aligned, allocate a smaller folio */1943 if (index & ((1UL << order) - 1))1944 order = __ffs(index);1945 1946 do {1947 gfp_t alloc_gfp = gfp;1948 1949 err = -ENOMEM;1950 if (order > min_order)1951 alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN;1952 folio = filemap_alloc_folio(alloc_gfp, order);1953 if (!folio)1954 continue;1955 1956 /* Init accessed so avoid atomic mark_page_accessed later */1957 if (fgp_flags & FGP_ACCESSED)1958 __folio_set_referenced(folio);1959 1960 err = filemap_add_folio(mapping, folio, index, gfp);1961 if (!err)1962 break;1963 folio_put(folio);1964 folio = NULL;1965 } while (order-- > min_order);1966 1967 if (err == -EEXIST)1968 goto repeat;1969 if (err)1970 return ERR_PTR(err);1971 /*1972 * filemap_add_folio locks the page, and for mmap1973 * we expect an unlocked page.1974 */1975 if (folio && (fgp_flags & FGP_FOR_MMAP))1976 folio_unlock(folio);1977 }1978 1979 if (!folio)1980 return ERR_PTR(-ENOENT);1981 return folio;1982}1983EXPORT_SYMBOL(__filemap_get_folio);1984 1985static inline struct folio *find_get_entry(struct xa_state *xas, pgoff_t max,1986 xa_mark_t mark)1987{1988 struct folio *folio;1989 1990retry:1991 if (mark == XA_PRESENT)1992 folio = xas_find(xas, max);1993 else1994 folio = xas_find_marked(xas, max, mark);1995 1996 if (xas_retry(xas, folio))1997 goto retry;1998 /*1999 * A shadow entry of a recently evicted page, a swap2000 * entry from shmem/tmpfs or a DAX entry. Return it2001 * without attempting to raise page count.2002 */2003 if (!folio || xa_is_value(folio))2004 return folio;2005 2006 if (!folio_try_get(folio))2007 goto reset;2008 2009 if (unlikely(folio != xas_reload(xas))) {2010 folio_put(folio);2011 goto reset;2012 }2013 2014 return folio;2015reset:2016 xas_reset(xas);2017 goto retry;2018}2019 2020/**2021 * find_get_entries - gang pagecache lookup2022 * @mapping: The address_space to search2023 * @start: The starting page cache index2024 * @end: The final page index (inclusive).2025 * @fbatch: Where the resulting entries are placed.2026 * @indices: The cache indices corresponding to the entries in @entries2027 *2028 * find_get_entries() will search for and return a batch of entries in2029 * the mapping. The entries are placed in @fbatch. find_get_entries()2030 * takes a reference on any actual folios it returns.2031 *2032 * The entries have ascending indexes. The indices may not be consecutive2033 * due to not-present entries or large folios.2034 *2035 * Any shadow entries of evicted folios, or swap entries from2036 * shmem/tmpfs, are included in the returned array.2037 *2038 * Return: The number of entries which were found.2039 */2040unsigned find_get_entries(struct address_space *mapping, pgoff_t *start,2041 pgoff_t end, struct folio_batch *fbatch, pgoff_t *indices)2042{2043 XA_STATE(xas, &mapping->i_pages, *start);2044 struct folio *folio;2045 2046 rcu_read_lock();2047 while ((folio = find_get_entry(&xas, end, XA_PRESENT)) != NULL) {2048 indices[fbatch->nr] = xas.xa_index;2049 if (!folio_batch_add(fbatch, folio))2050 break;2051 }2052 2053 if (folio_batch_count(fbatch)) {2054 unsigned long nr;2055 int idx = folio_batch_count(fbatch) - 1;2056 2057 folio = fbatch->folios[idx];2058 if (!xa_is_value(folio))2059 nr = folio_nr_pages(folio);2060 else2061 nr = 1 << xa_get_order(&mapping->i_pages, indices[idx]);2062 *start = round_down(indices[idx] + nr, nr);2063 }2064 rcu_read_unlock();2065 2066 return folio_batch_count(fbatch);2067}2068 2069/**2070 * find_lock_entries - Find a batch of pagecache entries.2071 * @mapping: The address_space to search.2072 * @start: The starting page cache index.2073 * @end: The final page index (inclusive).2074 * @fbatch: Where the resulting entries are placed.2075 * @indices: The cache indices of the entries in @fbatch.2076 *2077 * find_lock_entries() will return a batch of entries from @mapping.2078 * Swap, shadow and DAX entries are included. Folios are returned2079 * locked and with an incremented refcount. Folios which are locked2080 * by somebody else or under writeback are skipped. Folios which are2081 * partially outside the range are not returned.2082 *2083 * The entries have ascending indexes. The indices may not be consecutive2084 * due to not-present entries, large folios, folios which could not be2085 * locked or folios under writeback.2086 *2087 * Return: The number of entries which were found.2088 */2089unsigned find_lock_entries(struct address_space *mapping, pgoff_t *start,2090 pgoff_t end, struct folio_batch *fbatch, pgoff_t *indices)2091{2092 XA_STATE(xas, &mapping->i_pages, *start);2093 struct folio *folio;2094 2095 rcu_read_lock();2096 while ((folio = find_get_entry(&xas, end, XA_PRESENT))) {2097 unsigned long base;2098 unsigned long nr;2099 2100 if (!xa_is_value(folio)) {2101 nr = folio_nr_pages(folio);2102 base = folio->index;2103 /* Omit large folio which begins before the start */2104 if (base < *start)2105 goto put;2106 /* Omit large folio which extends beyond the end */2107 if (base + nr - 1 > end)2108 goto put;2109 if (!folio_trylock(folio))2110 goto put;2111 if (folio->mapping != mapping ||2112 folio_test_writeback(folio))2113 goto unlock;2114 VM_BUG_ON_FOLIO(!folio_contains(folio, xas.xa_index),2115 folio);2116 } else {2117 nr = 1 << xas_get_order(&xas);2118 base = xas.xa_index & ~(nr - 1);2119 /* Omit order>0 value which begins before the start */2120 if (base < *start)2121 continue;2122 /* Omit order>0 value which extends beyond the end */2123 if (base + nr - 1 > end)2124 break;2125 }2126 2127 /* Update start now so that last update is correct on return */2128 *start = base + nr;2129 indices[fbatch->nr] = xas.xa_index;2130 if (!folio_batch_add(fbatch, folio))2131 break;2132 continue;2133unlock:2134 folio_unlock(folio);2135put:2136 folio_put(folio);2137 }2138 rcu_read_unlock();2139 2140 return folio_batch_count(fbatch);2141}2142 2143/**2144 * filemap_get_folios - Get a batch of folios2145 * @mapping: The address_space to search2146 * @start: The starting page index2147 * @end: The final page index (inclusive)2148 * @fbatch: The batch to fill.2149 *2150 * Search for and return a batch of folios in the mapping starting at2151 * index @start and up to index @end (inclusive). The folios are returned2152 * in @fbatch with an elevated reference count.2153 *2154 * Return: The number of folios which were found.2155 * We also update @start to index the next folio for the traversal.2156 */2157unsigned filemap_get_folios(struct address_space *mapping, pgoff_t *start,2158 pgoff_t end, struct folio_batch *fbatch)2159{2160 return filemap_get_folios_tag(mapping, start, end, XA_PRESENT, fbatch);2161}2162EXPORT_SYMBOL(filemap_get_folios);2163 2164/**2165 * filemap_get_folios_contig - Get a batch of contiguous folios2166 * @mapping: The address_space to search2167 * @start: The starting page index2168 * @end: The final page index (inclusive)2169 * @fbatch: The batch to fill2170 *2171 * filemap_get_folios_contig() works exactly like filemap_get_folios(),2172 * except the returned folios are guaranteed to be contiguous. This may2173 * not return all contiguous folios if the batch gets filled up.2174 *2175 * Return: The number of folios found.2176 * Also update @start to be positioned for traversal of the next folio.2177 */2178 2179unsigned filemap_get_folios_contig(struct address_space *mapping,2180 pgoff_t *start, pgoff_t end, struct folio_batch *fbatch)2181{2182 XA_STATE(xas, &mapping->i_pages, *start);2183 unsigned long nr;2184 struct folio *folio;2185 2186 rcu_read_lock();2187 2188 for (folio = xas_load(&xas); folio && xas.xa_index <= end;2189 folio = xas_next(&xas)) {2190 if (xas_retry(&xas, folio))2191 continue;2192 /*2193 * If the entry has been swapped out, we can stop looking.2194 * No current caller is looking for DAX entries.2195 */2196 if (xa_is_value(folio))2197 goto update_start;2198 2199 /* If we landed in the middle of a THP, continue at its end. */2200 if (xa_is_sibling(folio))2201 goto update_start;2202 2203 if (!folio_try_get(folio))2204 goto retry;2205 2206 if (unlikely(folio != xas_reload(&xas)))2207 goto put_folio;2208 2209 if (!folio_batch_add(fbatch, folio)) {2210 nr = folio_nr_pages(folio);2211 *start = folio->index + nr;2212 goto out;2213 }2214 continue;2215put_folio:2216 folio_put(folio);2217 2218retry:2219 xas_reset(&xas);2220 }2221 2222update_start:2223 nr = folio_batch_count(fbatch);2224 2225 if (nr) {2226 folio = fbatch->folios[nr - 1];2227 *start = folio_next_index(folio);2228 }2229out:2230 rcu_read_unlock();2231 return folio_batch_count(fbatch);2232}2233EXPORT_SYMBOL(filemap_get_folios_contig);2234 2235/**2236 * filemap_get_folios_tag - Get a batch of folios matching @tag2237 * @mapping: The address_space to search2238 * @start: The starting page index2239 * @end: The final page index (inclusive)2240 * @tag: The tag index2241 * @fbatch: The batch to fill2242 *2243 * The first folio may start before @start; if it does, it will contain2244 * @start. The final folio may extend beyond @end; if it does, it will2245 * contain @end. The folios have ascending indices. There may be gaps2246 * between the folios if there are indices which have no folio in the2247 * page cache. If folios are added to or removed from the page cache2248 * while this is running, they may or may not be found by this call.2249 * Only returns folios that are tagged with @tag.2250 *2251 * Return: The number of folios found.2252 * Also update @start to index the next folio for traversal.2253 */2254unsigned filemap_get_folios_tag(struct address_space *mapping, pgoff_t *start,2255 pgoff_t end, xa_mark_t tag, struct folio_batch *fbatch)2256{2257 XA_STATE(xas, &mapping->i_pages, *start);2258 struct folio *folio;2259 2260 rcu_read_lock();2261 while ((folio = find_get_entry(&xas, end, tag)) != NULL) {2262 /*2263 * Shadow entries should never be tagged, but this iteration2264 * is lockless so there is a window for page reclaim to evict2265 * a page we saw tagged. Skip over it.2266 */2267 if (xa_is_value(folio))2268 continue;2269 if (!folio_batch_add(fbatch, folio)) {2270 unsigned long nr = folio_nr_pages(folio);2271 *start = folio->index + nr;2272 goto out;2273 }2274 }2275 /*2276 * We come here when there is no page beyond @end. We take care to not2277 * overflow the index @start as it confuses some of the callers. This2278 * breaks the iteration when there is a page at index -1 but that is2279 * already broke anyway.2280 */2281 if (end == (pgoff_t)-1)2282 *start = (pgoff_t)-1;2283 else2284 *start = end + 1;2285out:2286 rcu_read_unlock();2287 2288 return folio_batch_count(fbatch);2289}2290EXPORT_SYMBOL(filemap_get_folios_tag);2291 2292/*2293 * CD/DVDs are error prone. When a medium error occurs, the driver may fail2294 * a _large_ part of the i/o request. Imagine the worst scenario:2295 *2296 * ---R__________________________________________B__________2297 * ^ reading here ^ bad block(assume 4k)2298 *2299 * read(R) => miss => readahead(R...B) => media error => frustrating retries2300 * => failing the whole request => read(R) => read(R+1) =>2301 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>2302 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>2303 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......2304 *2305 * It is going insane. Fix it by quickly scaling down the readahead size.2306 */2307static void shrink_readahead_size_eio(struct file_ra_state *ra)2308{2309 ra->ra_pages /= 4;2310}2311 2312/*2313 * filemap_get_read_batch - Get a batch of folios for read2314 *2315 * Get a batch of folios which represent a contiguous range of bytes in2316 * the file. No exceptional entries will be returned. If @index is in2317 * the middle of a folio, the entire folio will be returned. The last2318 * folio in the batch may have the readahead flag set or the uptodate flag2319 * clear so that the caller can take the appropriate action.2320 */2321static void filemap_get_read_batch(struct address_space *mapping,2322 pgoff_t index, pgoff_t max, struct folio_batch *fbatch)2323{2324 XA_STATE(xas, &mapping->i_pages, index);2325 struct folio *folio;2326 2327 rcu_read_lock();2328 for (folio = xas_load(&xas); folio; folio = xas_next(&xas)) {2329 if (xas_retry(&xas, folio))2330 continue;2331 if (xas.xa_index > max || xa_is_value(folio))2332 break;2333 if (xa_is_sibling(folio))2334 break;2335 if (!folio_try_get(folio))2336 goto retry;2337 2338 if (unlikely(folio != xas_reload(&xas)))2339 goto put_folio;2340 2341 if (!folio_batch_add(fbatch, folio))2342 break;2343 if (!folio_test_uptodate(folio))2344 break;2345 if (folio_test_readahead(folio))2346 break;2347 xas_advance(&xas, folio_next_index(folio) - 1);2348 continue;2349put_folio:2350 folio_put(folio);2351retry:2352 xas_reset(&xas);2353 }2354 rcu_read_unlock();2355}2356 2357static HWJS_SUSPENDS int filemap_read_folio(struct file *file, filler_t filler,2358 struct folio *folio)2359{2360 bool workingset = folio_test_workingset(folio);2361 unsigned long pflags;2362 int error;2363 2364 /* Start the actual read. The read will unlock the page. */2365 if (unlikely(workingset))2366 psi_memstall_enter(&pflags);2367 error = filler(file, folio);2368 if (unlikely(workingset))2369 psi_memstall_leave(&pflags);2370 if (error)2371 return error;2372 2373 error = folio_wait_locked_killable(folio);2374 if (error)2375 return error;2376 if (folio_test_uptodate(folio))2377 return 0;2378 if (file)2379 shrink_readahead_size_eio(&file->f_ra);2380 return -EIO;2381}2382 2383static HWJS_SUSPENDS bool filemap_range_uptodate(struct address_space *mapping,2384 loff_t pos, size_t count, struct folio *folio,2385 bool need_uptodate)2386{2387 if (folio_test_uptodate(folio))2388 return true;2389 /* pipes can't handle partially uptodate pages */2390 if (need_uptodate)2391 return false;2392 if (!mapping->a_ops->is_partially_uptodate)2393 return false;2394 if (mapping->host->i_blkbits >= folio_shift(folio))2395 return false;2396 2397 if (folio_pos(folio) > pos) {2398 count -= folio_pos(folio) - pos;2399 pos = 0;2400 } else {2401 pos -= folio_pos(folio);2402 }2403 2404 return mapping->a_ops->is_partially_uptodate(folio, pos, count);2405}2406 2407static HWJS_SUSPENDS int filemap_update_page(struct kiocb *iocb,2408 struct address_space *mapping, size_t count,2409 struct folio *folio, bool need_uptodate)2410{2411 int error;2412 2413 if (iocb->ki_flags & IOCB_NOWAIT) {2414 if (!filemap_invalidate_trylock_shared(mapping))2415 return -EAGAIN;2416 } else {2417 filemap_invalidate_lock_shared(mapping);2418 }2419 2420 if (!folio_trylock(folio)) {2421 error = -EAGAIN;2422 if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO))2423 goto unlock_mapping;2424 if (!(iocb->ki_flags & IOCB_WAITQ)) {2425 filemap_invalidate_unlock_shared(mapping);2426 /*2427 * This is where we usually end up waiting for a2428 * previously submitted readahead to finish.2429 */2430 folio_put_wait_locked(folio, TASK_KILLABLE);2431 return AOP_TRUNCATED_PAGE;2432 }2433 error = __folio_lock_async(folio, iocb->ki_waitq);2434 if (error)2435 goto unlock_mapping;2436 }2437 2438 error = AOP_TRUNCATED_PAGE;2439 if (!folio->mapping)2440 goto unlock;2441 2442 error = 0;2443 if (filemap_range_uptodate(mapping, iocb->ki_pos, count, folio,2444 need_uptodate))2445 goto unlock;2446 2447 error = -EAGAIN;2448 if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ))2449 goto unlock;2450 2451 error = filemap_read_folio(iocb->ki_filp, mapping->a_ops->read_folio,2452 folio);2453 goto unlock_mapping;2454unlock:2455 folio_unlock(folio);2456unlock_mapping:2457 filemap_invalidate_unlock_shared(mapping);2458 if (error == AOP_TRUNCATED_PAGE)2459 folio_put(folio);2460 return error;2461}2462 2463static HWJS_SUSPENDS int filemap_create_folio(struct file *file,2464 struct address_space *mapping, loff_t pos,2465 struct folio_batch *fbatch)2466{2467 struct folio *folio;2468 int error;2469 unsigned int min_order = mapping_min_folio_order(mapping);2470 pgoff_t index;2471 2472 folio = filemap_alloc_folio(mapping_gfp_mask(mapping), min_order);2473 if (!folio)2474 return -ENOMEM;2475 2476 /*2477 * Protect against truncate / hole punch. Grabbing invalidate_lock2478 * here assures we cannot instantiate and bring uptodate new2479 * pagecache folios after evicting page cache during truncate2480 * and before actually freeing blocks. Note that we could2481 * release invalidate_lock after inserting the folio into2482 * the page cache as the locked folio would then be enough to2483 * synchronize with hole punching. But there are code paths2484 * such as filemap_update_page() filling in partially uptodate2485 * pages or ->readahead() that need to hold invalidate_lock2486 * while mapping blocks for IO so let's hold the lock here as2487 * well to keep locking rules simple.2488 */2489 filemap_invalidate_lock_shared(mapping);2490 index = (pos >> (PAGE_SHIFT + min_order)) << min_order;2491 error = filemap_add_folio(mapping, folio, index,2492 mapping_gfp_constraint(mapping, GFP_KERNEL));2493 if (error == -EEXIST)2494 error = AOP_TRUNCATED_PAGE;2495 if (error)2496 goto error;2497 2498 error = filemap_read_folio(file, mapping->a_ops->read_folio, folio);2499 if (error)2500 goto error;2501 2502 filemap_invalidate_unlock_shared(mapping);2503 folio_batch_add(fbatch, folio);2504 return 0;2505error:2506 filemap_invalidate_unlock_shared(mapping);2507 folio_put(folio);2508 return error;2509}2510 2511static int filemap_readahead(struct kiocb *iocb, struct file *file,2512 struct address_space *mapping, struct folio *folio,2513 pgoff_t last_index)2514{2515 DEFINE_READAHEAD(ractl, file, &file->f_ra, mapping, folio->index);2516 2517 if (iocb->ki_flags & IOCB_NOIO)2518 return -EAGAIN;2519 page_cache_async_ra(&ractl, folio, last_index - folio->index);2520 return 0;2521}2522 2523static HWJS_SUSPENDS int filemap_get_pages(struct kiocb *iocb, size_t count,2524 struct folio_batch *fbatch, bool need_uptodate)2525{2526 struct file *filp = iocb->ki_filp;2527 struct address_space *mapping = filp->f_mapping;2528 struct file_ra_state *ra = &filp->f_ra;2529 pgoff_t index = iocb->ki_pos >> PAGE_SHIFT;2530 pgoff_t last_index;2531 struct folio *folio;2532 unsigned int flags;2533 int err = 0;2534 2535 /* "last_index" is the index of the page beyond the end of the read */2536 last_index = DIV_ROUND_UP(iocb->ki_pos + count, PAGE_SIZE);2537retry:2538 if (fatal_signal_pending(current))2539 return -EINTR;2540 2541 filemap_get_read_batch(mapping, index, last_index - 1, fbatch);2542 if (!folio_batch_count(fbatch)) {2543 if (iocb->ki_flags & IOCB_NOIO)2544 return -EAGAIN;2545 if (iocb->ki_flags & IOCB_NOWAIT)2546 flags = memalloc_noio_save();2547 page_cache_sync_readahead(mapping, ra, filp, index,2548 last_index - index);2549 if (iocb->ki_flags & IOCB_NOWAIT)2550 memalloc_noio_restore(flags);2551 filemap_get_read_batch(mapping, index, last_index - 1, fbatch);2552 }2553 if (!folio_batch_count(fbatch)) {2554 if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))2555 return -EAGAIN;2556 err = filemap_create_folio(filp, mapping, iocb->ki_pos, fbatch);2557 if (err == AOP_TRUNCATED_PAGE)2558 goto retry;2559 return err;2560 }2561 2562 folio = fbatch->folios[folio_batch_count(fbatch) - 1];2563 if (folio_test_readahead(folio)) {2564 err = filemap_readahead(iocb, filp, mapping, folio, last_index);2565 if (err)2566 goto err;2567 }2568 if (!folio_test_uptodate(folio)) {2569 if ((iocb->ki_flags & IOCB_WAITQ) &&2570 folio_batch_count(fbatch) > 1)2571 iocb->ki_flags |= IOCB_NOWAIT;2572 err = filemap_update_page(iocb, mapping, count, folio,2573 need_uptodate);2574 if (err)2575 goto err;2576 }2577 2578 trace_mm_filemap_get_pages(mapping, index, last_index - 1);2579 return 0;2580err:2581 if (err < 0)2582 folio_put(folio);2583 if (likely(--fbatch->nr))2584 return 0;2585 if (err == AOP_TRUNCATED_PAGE)2586 goto retry;2587 return err;2588}2589 2590static inline bool pos_same_folio(loff_t pos1, loff_t pos2, struct folio *folio)2591{2592 unsigned int shift = folio_shift(folio);2593 2594 return (pos1 >> shift == pos2 >> shift);2595}2596 2597/**2598 * filemap_read - Read data from the page cache.2599 * @iocb: The iocb to read.2600 * @iter: Destination for the data.2601 * @already_read: Number of bytes already read by the caller.2602 *2603 * Copies data from the page cache. If the data is not currently present,2604 * uses the readahead and read_folio address_space operations to fetch it.2605 *2606 * Return: Total number of bytes copied, including those already read by2607 * the caller. If an error happens before any bytes are copied, returns2608 * a negative error number.2609 */2610ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter,2611 ssize_t already_read)2612{2613 struct file *filp = iocb->ki_filp;2614 struct file_ra_state *ra = &filp->f_ra;2615 struct address_space *mapping = filp->f_mapping;2616 struct inode *inode = mapping->host;2617 struct folio_batch fbatch;2618 int i, error = 0;2619 bool writably_mapped;2620 loff_t isize, end_offset;2621 loff_t last_pos = ra->prev_pos;2622 2623 if (unlikely(iocb->ki_pos >= inode->i_sb->s_maxbytes))2624 return 0;2625 if (unlikely(!iov_iter_count(iter)))2626 return 0;2627 2628 iov_iter_truncate(iter, inode->i_sb->s_maxbytes - iocb->ki_pos);2629 folio_batch_init(&fbatch);2630 2631 do {2632 cond_resched();2633 2634 /*2635 * If we've already successfully copied some data, then we2636 * can no longer safely return -EIOCBQUEUED. Hence mark2637 * an async read NOWAIT at that point.2638 */2639 if ((iocb->ki_flags & IOCB_WAITQ) && already_read)2640 iocb->ki_flags |= IOCB_NOWAIT;2641 2642 if (unlikely(iocb->ki_pos >= i_size_read(inode)))2643 break;2644 2645 error = filemap_get_pages(iocb, iter->count, &fbatch, false);2646 if (error < 0)2647 break;2648 2649 /*2650 * i_size must be checked after we know the pages are Uptodate.2651 *2652 * Checking i_size after the check allows us to calculate2653 * the correct value for "nr", which means the zero-filled2654 * part of the page is not copied back to userspace (unless2655 * another truncate extends the file - this is desired though).2656 */2657 isize = i_size_read(inode);2658 if (unlikely(iocb->ki_pos >= isize))2659 goto put_folios;2660 end_offset = min_t(loff_t, isize, iocb->ki_pos + iter->count);2661 2662 /*2663 * Once we start copying data, we don't want to be touching any2664 * cachelines that might be contended:2665 */2666 writably_mapped = mapping_writably_mapped(mapping);2667 2668 /*2669 * When a read accesses the same folio several times, only2670 * mark it as accessed the first time.2671 */2672 if (!pos_same_folio(iocb->ki_pos, last_pos - 1,2673 fbatch.folios[0]))2674 folio_mark_accessed(fbatch.folios[0]);2675 2676 for (i = 0; i < folio_batch_count(&fbatch); i++) {2677 struct folio *folio = fbatch.folios[i];2678 size_t fsize = folio_size(folio);2679 size_t offset = iocb->ki_pos & (fsize - 1);2680 size_t bytes = min_t(loff_t, end_offset - iocb->ki_pos,2681 fsize - offset);2682 size_t copied;2683 2684 if (end_offset < folio_pos(folio))2685 break;2686 if (i > 0)2687 folio_mark_accessed(folio);2688 /*2689 * If users can be writing to this folio using arbitrary2690 * virtual addresses, take care of potential aliasing2691 * before reading the folio on the kernel side.2692 */2693 if (writably_mapped)2694 flush_dcache_folio(folio);2695 2696 copied = copy_folio_to_iter(folio, offset, bytes, iter);2697 2698 already_read += copied;2699 iocb->ki_pos += copied;2700 last_pos = iocb->ki_pos;2701 2702 if (copied < bytes) {2703 error = -EFAULT;2704 break;2705 }2706 }2707put_folios:2708 for (i = 0; i < folio_batch_count(&fbatch); i++)2709 folio_put(fbatch.folios[i]);2710 folio_batch_init(&fbatch);2711 } while (iov_iter_count(iter) && iocb->ki_pos < isize && !error);2712 2713 file_accessed(filp);2714 ra->prev_pos = last_pos;2715 return already_read ? already_read : error;2716}2717EXPORT_SYMBOL_GPL(filemap_read);2718 2719int kiocb_write_and_wait(struct kiocb *iocb, size_t count)2720{2721 struct address_space *mapping = iocb->ki_filp->f_mapping;2722 loff_t pos = iocb->ki_pos;2723 loff_t end = pos + count - 1;2724 2725 if (iocb->ki_flags & IOCB_NOWAIT) {2726 if (filemap_range_needs_writeback(mapping, pos, end))2727 return -EAGAIN;2728 return 0;2729 }2730 2731 return filemap_write_and_wait_range(mapping, pos, end);2732}2733EXPORT_SYMBOL_GPL(kiocb_write_and_wait);2734 2735int filemap_invalidate_pages(struct address_space *mapping,2736 loff_t pos, loff_t end, bool nowait)2737{2738 int ret;2739 2740 if (nowait) {2741 /* we could block if there are any pages in the range */2742 if (filemap_range_has_page(mapping, pos, end))2743 return -EAGAIN;2744 } else {2745 ret = filemap_write_and_wait_range(mapping, pos, end);2746 if (ret)2747 return ret;2748 }2749 2750 /*2751 * After a write we want buffered reads to be sure to go to disk to get2752 * the new data. We invalidate clean cached page from the region we're2753 * about to write. We do this *before* the write so that we can return2754 * without clobbering -EIOCBQUEUED from ->direct_IO().2755 */2756 return invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT,2757 end >> PAGE_SHIFT);2758}2759 2760int kiocb_invalidate_pages(struct kiocb *iocb, size_t count)2761{2762 struct address_space *mapping = iocb->ki_filp->f_mapping;2763 2764 return filemap_invalidate_pages(mapping, iocb->ki_pos,2765 iocb->ki_pos + count - 1,2766 iocb->ki_flags & IOCB_NOWAIT);2767}2768EXPORT_SYMBOL_GPL(kiocb_invalidate_pages);2769 2770/**2771 * generic_file_read_iter - generic filesystem read routine2772 * @iocb: kernel I/O control block2773 * @iter: destination for the data read2774 *2775 * This is the "read_iter()" routine for all filesystems2776 * that can use the page cache directly.2777 *2778 * The IOCB_NOWAIT flag in iocb->ki_flags indicates that -EAGAIN shall2779 * be returned when no data can be read without waiting for I/O requests2780 * to complete; it doesn't prevent readahead.2781 *2782 * The IOCB_NOIO flag in iocb->ki_flags indicates that no new I/O2783 * requests shall be made for the read or for readahead. When no data2784 * can be read, -EAGAIN shall be returned. When readahead would be2785 * triggered, a partial, possibly empty read shall be returned.2786 *2787 * Return:2788 * * number of bytes copied, even for partial reads2789 * * negative error code (or 0 if IOCB_NOIO) if nothing was read2790 */2791ssize_t2792generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)2793{2794 size_t count = iov_iter_count(iter);2795 ssize_t retval = 0;2796 2797 if (!count)2798 return 0; /* skip atime */2799 2800 if (iocb->ki_flags & IOCB_DIRECT) {2801 struct file *file = iocb->ki_filp;2802 struct address_space *mapping = file->f_mapping;2803 struct inode *inode = mapping->host;2804 2805 retval = kiocb_write_and_wait(iocb, count);2806 if (retval < 0)2807 return retval;2808 file_accessed(file);2809 2810 retval = mapping->a_ops->direct_IO(iocb, iter);2811 if (retval >= 0) {2812 iocb->ki_pos += retval;2813 count -= retval;2814 }2815 if (retval != -EIOCBQUEUED)2816 iov_iter_revert(iter, count - iov_iter_count(iter));2817 2818 /*2819 * Btrfs can have a short DIO read if we encounter2820 * compressed extents, so if there was an error, or if2821 * we've already read everything we wanted to, or if2822 * there was a short read because we hit EOF, go ahead2823 * and return. Otherwise fallthrough to buffered io for2824 * the rest of the read. Buffered reads will not work for2825 * DAX files, so don't bother trying.2826 */2827 if (retval < 0 || !count || IS_DAX(inode))2828 return retval;2829 if (iocb->ki_pos >= i_size_read(inode))2830 return retval;2831 }2832 2833 return filemap_read(iocb, iter, retval);2834}2835EXPORT_SYMBOL(generic_file_read_iter);2836 2837/*2838 * Splice subpages from a folio into a pipe.2839 */2840size_t splice_folio_into_pipe(struct pipe_inode_info *pipe,2841 struct folio *folio, loff_t fpos, size_t size)2842{2843 struct page *page;2844 size_t spliced = 0, offset = offset_in_folio(folio, fpos);2845 2846 page = folio_page(folio, offset / PAGE_SIZE);2847 size = min(size, folio_size(folio) - offset);2848 offset %= PAGE_SIZE;2849 2850 while (spliced < size &&2851 !pipe_full(pipe->head, pipe->tail, pipe->max_usage)) {2852 struct pipe_buffer *buf = pipe_head_buf(pipe);2853 size_t part = min_t(size_t, PAGE_SIZE - offset, size - spliced);2854 2855 *buf = (struct pipe_buffer) {2856 .ops = &page_cache_pipe_buf_ops,2857 .page = page,2858 .offset = offset,2859 .len = part,2860 };2861 folio_get(folio);2862 pipe->head++;2863 page++;2864 spliced += part;2865 offset = 0;2866 }2867 2868 return spliced;2869}2870 2871/**2872 * filemap_splice_read - Splice data from a file's pagecache into a pipe2873 * @in: The file to read from2874 * @ppos: Pointer to the file position to read from2875 * @pipe: The pipe to splice into2876 * @len: The amount to splice2877 * @flags: The SPLICE_F_* flags2878 *2879 * This function gets folios from a file's pagecache and splices them into the2880 * pipe. Readahead will be called as necessary to fill more folios. This may2881 * be used for blockdevs also.2882 *2883 * Return: On success, the number of bytes read will be returned and *@ppos2884 * will be updated if appropriate; 0 will be returned if there is no more data2885 * to be read; -EAGAIN will be returned if the pipe had no space, and some2886 * other negative error code will be returned on error. A short read may occur2887 * if the pipe has insufficient space, we reach the end of the data or we hit a2888 * hole.2889 */2890ssize_t filemap_splice_read(struct file *in, loff_t *ppos,2891 struct pipe_inode_info *pipe,2892 size_t len, unsigned int flags)2893{2894 struct folio_batch fbatch;2895 struct kiocb iocb;2896 size_t total_spliced = 0, used, npages;2897 loff_t isize, end_offset;2898 bool writably_mapped;2899 int i, error = 0;2900 2901 if (unlikely(*ppos >= in->f_mapping->host->i_sb->s_maxbytes))2902 return 0;2903 2904 init_sync_kiocb(&iocb, in);2905 iocb.ki_pos = *ppos;2906 2907 /* Work out how much data we can actually add into the pipe */2908 used = pipe_occupancy(pipe->head, pipe->tail);2909 npages = max_t(ssize_t, pipe->max_usage - used, 0);2910 len = min_t(size_t, len, npages * PAGE_SIZE);2911 2912 folio_batch_init(&fbatch);2913 2914 do {2915 cond_resched();2916 2917 if (*ppos >= i_size_read(in->f_mapping->host))2918 break;2919 2920 iocb.ki_pos = *ppos;2921 error = filemap_get_pages(&iocb, len, &fbatch, true);2922 if (error < 0)2923 break;2924 2925 /*2926 * i_size must be checked after we know the pages are Uptodate.2927 *2928 * Checking i_size after the check allows us to calculate2929 * the correct value for "nr", which means the zero-filled2930 * part of the page is not copied back to userspace (unless2931 * another truncate extends the file - this is desired though).2932 */2933 isize = i_size_read(in->f_mapping->host);2934 if (unlikely(*ppos >= isize))2935 break;2936 end_offset = min_t(loff_t, isize, *ppos + len);2937 2938 /*2939 * Once we start copying data, we don't want to be touching any2940 * cachelines that might be contended:2941 */2942 writably_mapped = mapping_writably_mapped(in->f_mapping);2943 2944 for (i = 0; i < folio_batch_count(&fbatch); i++) {2945 struct folio *folio = fbatch.folios[i];2946 size_t n;2947 2948 if (folio_pos(folio) >= end_offset)2949 goto out;2950 folio_mark_accessed(folio);2951 2952 /*2953 * If users can be writing to this folio using arbitrary2954 * virtual addresses, take care of potential aliasing2955 * before reading the folio on the kernel side.2956 */2957 if (writably_mapped)2958 flush_dcache_folio(folio);2959 2960 n = min_t(loff_t, len, isize - *ppos);2961 n = splice_folio_into_pipe(pipe, folio, *ppos, n);2962 if (!n)2963 goto out;2964 len -= n;2965 total_spliced += n;2966 *ppos += n;2967 in->f_ra.prev_pos = *ppos;2968 if (pipe_full(pipe->head, pipe->tail, pipe->max_usage))2969 goto out;2970 }2971 2972 folio_batch_release(&fbatch);2973 } while (len);2974 2975out:2976 folio_batch_release(&fbatch);2977 file_accessed(in);2978 2979 return total_spliced ? total_spliced : error;2980}2981EXPORT_SYMBOL(filemap_splice_read);2982 2983static HWJS_SUSPENDS inline loff_t folio_seek_hole_data(struct xa_state *xas,2984 struct address_space *mapping, struct folio *folio,2985 loff_t start, loff_t end, bool seek_data)2986{2987 const struct address_space_operations *ops = mapping->a_ops;2988 size_t offset, bsz = i_blocksize(mapping->host);2989 2990 if (xa_is_value(folio) || folio_test_uptodate(folio))2991 return seek_data ? start : end;2992 if (!ops->is_partially_uptodate)2993 return seek_data ? end : start;2994 2995 xas_pause(xas);2996 rcu_read_unlock();2997 folio_lock(folio);2998 if (unlikely(folio->mapping != mapping))2999 goto unlock;3000 3001 offset = offset_in_folio(folio, start) & ~(bsz - 1);3002 3003 do {3004 if (ops->is_partially_uptodate(folio, offset, bsz) ==3005 seek_data)3006 break;3007 start = (start + bsz) & ~(bsz - 1);3008 offset += bsz;3009 } while (offset < folio_size(folio));3010unlock:3011 folio_unlock(folio);3012 rcu_read_lock();3013 return start;3014}3015 3016static inline size_t seek_folio_size(struct xa_state *xas, struct folio *folio)3017{3018 if (xa_is_value(folio))3019 return PAGE_SIZE << xas_get_order(xas);3020 return folio_size(folio);3021}3022 3023/**3024 * mapping_seek_hole_data - Seek for SEEK_DATA / SEEK_HOLE in the page cache.3025 * @mapping: Address space to search.3026 * @start: First byte to consider.3027 * @end: Limit of search (exclusive).3028 * @whence: Either SEEK_HOLE or SEEK_DATA.3029 *3030 * If the page cache knows which blocks contain holes and which blocks3031 * contain data, your filesystem can use this function to implement3032 * SEEK_HOLE and SEEK_DATA. This is useful for filesystems which are3033 * entirely memory-based such as tmpfs, and filesystems which support3034 * unwritten extents.3035 *3036 * Return: The requested offset on success, or -ENXIO if @whence specifies3037 * SEEK_DATA and there is no data after @start. There is an implicit hole3038 * after @end - 1, so SEEK_HOLE returns @end if all the bytes between @start3039 * and @end contain data.3040 */3041loff_t mapping_seek_hole_data(struct address_space *mapping, loff_t start,3042 loff_t end, int whence)3043{3044 XA_STATE(xas, &mapping->i_pages, start >> PAGE_SHIFT);3045 pgoff_t max = (end - 1) >> PAGE_SHIFT;3046 bool seek_data = (whence == SEEK_DATA);3047 struct folio *folio;3048 3049 if (end <= start)3050 return -ENXIO;3051 3052 rcu_read_lock();3053 while ((folio = find_get_entry(&xas, max, XA_PRESENT))) {3054 loff_t pos = (u64)xas.xa_index << PAGE_SHIFT;3055 size_t seek_size;3056 3057 if (start < pos) {3058 if (!seek_data)3059 goto unlock;3060 start = pos;3061 }3062 3063 seek_size = seek_folio_size(&xas, folio);3064 pos = round_up((u64)pos + 1, seek_size);3065 start = folio_seek_hole_data(&xas, mapping, folio, start, pos,3066 seek_data);3067 if (start < pos)3068 goto unlock;3069 if (start >= end)3070 break;3071 if (seek_size > PAGE_SIZE)3072 xas_set(&xas, pos >> PAGE_SHIFT);3073 if (!xa_is_value(folio))3074 folio_put(folio);3075 }3076 if (seek_data)3077 start = -ENXIO;3078unlock:3079 rcu_read_unlock();3080 if (folio && !xa_is_value(folio))3081 folio_put(folio);3082 if (start > end)3083 return end;3084 return start;3085}3086 3087#ifdef CONFIG_MMU3088#define MMAP_LOTSAMISS (100)3089/*3090 * lock_folio_maybe_drop_mmap - lock the page, possibly dropping the mmap_lock3091 * @vmf - the vm_fault for this fault.3092 * @folio - the folio to lock.3093 * @fpin - the pointer to the file we may pin (or is already pinned).3094 *3095 * This works similar to lock_folio_or_retry in that it can drop the3096 * mmap_lock. It differs in that it actually returns the folio locked3097 * if it returns 1 and 0 if it couldn't lock the folio. If we did have3098 * to drop the mmap_lock then fpin will point to the pinned file and3099 * needs to be fput()'ed at a later point.3100 */3101static int lock_folio_maybe_drop_mmap(struct vm_fault *vmf, struct folio *folio,3102 struct file **fpin)3103{3104 if (folio_trylock(folio))3105 return 1;3106 3107 /*3108 * NOTE! This will make us return with VM_FAULT_RETRY, but with3109 * the fault lock still held. That's how FAULT_FLAG_RETRY_NOWAIT3110 * is supposed to work. We have way too many special cases..3111 */3112 if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)3113 return 0;3114 3115 *fpin = maybe_unlock_mmap_for_io(vmf, *fpin);3116 if (vmf->flags & FAULT_FLAG_KILLABLE) {3117 if (__folio_lock_killable(folio)) {3118 /*3119 * We didn't have the right flags to drop the3120 * fault lock, but all fault_handlers only check3121 * for fatal signals if we return VM_FAULT_RETRY,3122 * so we need to drop the fault lock here and3123 * return 0 if we don't have a fpin.3124 */3125 if (*fpin == NULL)3126 release_fault_lock(vmf);3127 return 0;3128 }3129 } else3130 __folio_lock(folio);3131 3132 return 1;3133}3134 3135/*3136 * Synchronous readahead happens when we don't even find a page in the page3137 * cache at all. We don't want to perform IO under the mmap sem, so if we have3138 * to drop the mmap sem we return the file that was pinned in order for us to do3139 * that. If we didn't pin a file then we return NULL. The file that is3140 * returned needs to be fput()'ed when we're done with it.3141 */3142static HWJS_SUSPENDS struct file *do_sync_mmap_readahead(struct vm_fault *vmf)3143{3144 struct file *file = vmf->vma->vm_file;3145 struct file_ra_state *ra = &file->f_ra;3146 struct address_space *mapping = file->f_mapping;3147 DEFINE_READAHEAD(ractl, file, ra, mapping, vmf->pgoff);3148 struct file *fpin = NULL;3149 unsigned long vm_flags = vmf->vma->vm_flags;3150 unsigned int mmap_miss;3151 3152#ifdef CONFIG_TRANSPARENT_HUGEPAGE3153 /* Use the readahead code, even if readahead is disabled */3154 if ((vm_flags & VM_HUGEPAGE) && HPAGE_PMD_ORDER <= MAX_PAGECACHE_ORDER) {3155 fpin = maybe_unlock_mmap_for_io(vmf, fpin);3156 ractl._index &= ~((unsigned long)HPAGE_PMD_NR - 1);3157 ra->size = HPAGE_PMD_NR;3158 /*3159 * Fetch two PMD folios, so we get the chance to actually3160 * readahead, unless we've been told not to.3161 */3162 if (!(vm_flags & VM_RAND_READ))3163 ra->size *= 2;3164 ra->async_size = HPAGE_PMD_NR;3165 page_cache_ra_order(&ractl, ra, HPAGE_PMD_ORDER);3166 return fpin;3167 }3168#endif3169 3170 /* If we don't want any read-ahead, don't bother */3171 if (vm_flags & VM_RAND_READ)3172 return fpin;3173 if (!ra->ra_pages)3174 return fpin;3175 3176 if (vm_flags & VM_SEQ_READ) {3177 fpin = maybe_unlock_mmap_for_io(vmf, fpin);3178 page_cache_sync_ra(&ractl, ra->ra_pages);3179 return fpin;3180 }3181 3182 /* Avoid banging the cache line if not needed */3183 mmap_miss = READ_ONCE(ra->mmap_miss);3184 if (mmap_miss < MMAP_LOTSAMISS * 10)3185 WRITE_ONCE(ra->mmap_miss, ++mmap_miss);3186 3187 /*3188 * Do we miss much more than hit in this file? If so,3189 * stop bothering with read-ahead. It will only hurt.3190 */3191 if (mmap_miss > MMAP_LOTSAMISS)3192 return fpin;3193 3194 /*3195 * mmap read-around3196 */3197 fpin = maybe_unlock_mmap_for_io(vmf, fpin);3198 ra->start = max_t(long, 0, vmf->pgoff - ra->ra_pages / 2);3199 ra->size = ra->ra_pages;3200 ra->async_size = ra->ra_pages / 4;3201 ractl._index = ra->start;3202 page_cache_ra_order(&ractl, ra, 0);3203 return fpin;3204}3205 3206/*3207 * Asynchronous readahead happens when we find the page and PG_readahead,3208 * so we want to possibly extend the readahead further. We return the file that3209 * was pinned if we have to drop the mmap_lock in order to do IO.3210 */3211static HWJS_SUSPENDS struct file *do_async_mmap_readahead(struct vm_fault *vmf,3212 struct folio *folio)3213{3214 struct file *file = vmf->vma->vm_file;3215 struct file_ra_state *ra = &file->f_ra;3216 DEFINE_READAHEAD(ractl, file, ra, file->f_mapping, vmf->pgoff);3217 struct file *fpin = NULL;3218 unsigned int mmap_miss;3219 3220 /* If we don't want any read-ahead, don't bother */3221 if (vmf->vma->vm_flags & VM_RAND_READ || !ra->ra_pages)3222 return fpin;3223 3224 mmap_miss = READ_ONCE(ra->mmap_miss);3225 if (mmap_miss)3226 WRITE_ONCE(ra->mmap_miss, --mmap_miss);3227 3228 if (folio_test_readahead(folio)) {3229 fpin = maybe_unlock_mmap_for_io(vmf, fpin);3230 page_cache_async_ra(&ractl, folio, ra->ra_pages);3231 }3232 return fpin;3233}3234 3235static vm_fault_t filemap_fault_recheck_pte_none(struct vm_fault *vmf)3236{3237 struct vm_area_struct *vma = vmf->vma;3238 vm_fault_t ret = 0;3239 pte_t *ptep;3240 3241 /*3242 * We might have COW'ed a pagecache folio and might now have an mlocked3243 * anon folio mapped. The original pagecache folio is not mlocked and3244 * might have been evicted. During a read+clear/modify/write update of3245 * the PTE, such as done in do_numa_page()/change_pte_range(), we3246 * temporarily clear the PTE under PT lock and might detect it here as3247 * "none" when not holding the PT lock.3248 *3249 * Not rechecking the PTE under PT lock could result in an unexpected3250 * major fault in an mlock'ed region. Recheck only for this special3251 * scenario while holding the PT lock, to not degrade non-mlocked3252 * scenarios. Recheck the PTE without PT lock firstly, thereby reducing3253 * the number of times we hold PT lock.3254 */3255 if (!(vma->vm_flags & VM_LOCKED))3256 return 0;3257 3258 if (!(vmf->flags & FAULT_FLAG_ORIG_PTE_VALID))3259 return 0;3260 3261 ptep = pte_offset_map_nolock(vma->vm_mm, vmf->pmd, vmf->address,3262 &vmf->ptl);3263 if (unlikely(!ptep))3264 return VM_FAULT_NOPAGE;3265 3266 if (unlikely(!pte_none(ptep_get_lockless(ptep)))) {3267 ret = VM_FAULT_NOPAGE;3268 } else {3269 spin_lock(vmf->ptl);3270 if (unlikely(!pte_none(ptep_get(ptep))))3271 ret = VM_FAULT_NOPAGE;3272 spin_unlock(vmf->ptl);3273 }3274 pte_unmap(ptep);3275 return ret;3276}3277 3278/**3279 * filemap_fault - read in file data for page fault handling3280 * @vmf: struct vm_fault containing details of the fault3281 *3282 * filemap_fault() is invoked via the vma operations vector for a3283 * mapped memory region to read in file data during a page fault.3284 *3285 * The goto's are kind of ugly, but this streamlines the normal case of having3286 * it in the page cache, and handles the special cases reasonably without3287 * having a lot of duplicated code.3288 *3289 * vma->vm_mm->mmap_lock must be held on entry.3290 *3291 * If our return value has VM_FAULT_RETRY set, it's because the mmap_lock3292 * may be dropped before doing I/O or by lock_folio_maybe_drop_mmap().3293 *3294 * If our return value does not have VM_FAULT_RETRY set, the mmap_lock3295 * has not been released.3296 *3297 * We never return with VM_FAULT_RETRY and a bit from VM_FAULT_ERROR set.3298 *3299 * Return: bitwise-OR of %VM_FAULT_ codes.3300 */3301vm_fault_t filemap_fault(struct vm_fault *vmf)3302{3303 int error;3304 struct file *file = vmf->vma->vm_file;3305 struct file *fpin = NULL;3306 struct address_space *mapping = file->f_mapping;3307 struct inode *inode = mapping->host;3308 pgoff_t max_idx, index = vmf->pgoff;3309 struct folio *folio;3310 vm_fault_t ret = 0;3311 bool mapping_locked = false;3312 3313 max_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);3314 if (unlikely(index >= max_idx))3315 return VM_FAULT_SIGBUS;3316 3317 trace_mm_filemap_fault(mapping, index);3318 3319 /*3320 * Do we have something in the page cache already?3321 */3322 folio = filemap_get_folio(mapping, index);3323 if (likely(!IS_ERR(folio))) {3324 /*3325 * We found the page, so try async readahead before waiting for3326 * the lock.3327 */3328 if (!(vmf->flags & FAULT_FLAG_TRIED))3329 fpin = do_async_mmap_readahead(vmf, folio);3330 if (unlikely(!folio_test_uptodate(folio))) {3331 filemap_invalidate_lock_shared(mapping);3332 mapping_locked = true;3333 }3334 } else {3335 ret = filemap_fault_recheck_pte_none(vmf);3336 if (unlikely(ret))3337 return ret;3338 3339 /* No page in the page cache at all */3340 count_vm_event(PGMAJFAULT);3341 count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);3342 ret = VM_FAULT_MAJOR;3343 fpin = do_sync_mmap_readahead(vmf);3344retry_find:3345 /*3346 * See comment in filemap_create_folio() why we need3347 * invalidate_lock3348 */3349 if (!mapping_locked) {3350 filemap_invalidate_lock_shared(mapping);3351 mapping_locked = true;3352 }3353 folio = __filemap_get_folio(mapping, index,3354 FGP_CREAT|FGP_FOR_MMAP,3355 vmf->gfp_mask);3356 if (IS_ERR(folio)) {3357 if (fpin)3358 goto out_retry;3359 filemap_invalidate_unlock_shared(mapping);3360 return VM_FAULT_OOM;3361 }3362 }3363 3364 if (!lock_folio_maybe_drop_mmap(vmf, folio, &fpin))3365 goto out_retry;3366 3367 /* Did it get truncated? */3368 if (unlikely(folio->mapping != mapping)) {3369 folio_unlock(folio);3370 folio_put(folio);3371 goto retry_find;3372 }3373 VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio);3374 3375 /*3376 * We have a locked folio in the page cache, now we need to check3377 * that it's up-to-date. If not, it is going to be due to an error,3378 * or because readahead was otherwise unable to retrieve it.3379 */3380 if (unlikely(!folio_test_uptodate(folio))) {3381 /*3382 * If the invalidate lock is not held, the folio was in cache3383 * and uptodate and now it is not. Strange but possible since we3384 * didn't hold the page lock all the time. Let's drop3385 * everything, get the invalidate lock and try again.3386 */3387 if (!mapping_locked) {3388 folio_unlock(folio);3389 folio_put(folio);3390 goto retry_find;3391 }3392 3393 /*3394 * OK, the folio is really not uptodate. This can be because the3395 * VMA has the VM_RAND_READ flag set, or because an error3396 * arose. Let's read it in directly.3397 */3398 goto page_not_uptodate;3399 }3400 3401 /*3402 * We've made it this far and we had to drop our mmap_lock, now is the3403 * time to return to the upper layer and have it re-find the vma and3404 * redo the fault.3405 */3406 if (fpin) {3407 folio_unlock(folio);3408 goto out_retry;3409 }3410 if (mapping_locked)3411 filemap_invalidate_unlock_shared(mapping);3412 3413 /*3414 * Found the page and have a reference on it.3415 * We must recheck i_size under page lock.3416 */3417 max_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);3418 if (unlikely(index >= max_idx)) {3419 folio_unlock(folio);3420 folio_put(folio);3421 return VM_FAULT_SIGBUS;3422 }3423 3424 vmf->page = folio_file_page(folio, index);3425 return ret | VM_FAULT_LOCKED;3426 3427page_not_uptodate:3428 /*3429 * Umm, take care of errors if the page isn't up-to-date.3430 * Try to re-read it _once_. We do this synchronously,3431 * because there really aren't any performance issues here3432 * and we need to check for errors.3433 */3434 fpin = maybe_unlock_mmap_for_io(vmf, fpin);3435 error = filemap_read_folio(file, mapping->a_ops->read_folio, folio);3436 if (fpin)3437 goto out_retry;3438 folio_put(folio);3439 3440 if (!error || error == AOP_TRUNCATED_PAGE)3441 goto retry_find;3442 filemap_invalidate_unlock_shared(mapping);3443 3444 return VM_FAULT_SIGBUS;3445 3446out_retry:3447 /*3448 * We dropped the mmap_lock, we need to return to the fault handler to3449 * re-find the vma and come back and find our hopefully still populated3450 * page.3451 */3452 if (!IS_ERR(folio))3453 folio_put(folio);3454 if (mapping_locked)3455 filemap_invalidate_unlock_shared(mapping);3456 if (fpin)3457 fput(fpin);3458 return ret | VM_FAULT_RETRY;3459}3460EXPORT_SYMBOL(filemap_fault);3461 3462static HWJS_SUSPENDS bool filemap_map_pmd(struct vm_fault *vmf, struct folio *folio,3463 pgoff_t start)3464{3465 struct mm_struct *mm = vmf->vma->vm_mm;3466 3467 /* Huge page is mapped? No need to proceed. */3468 if (pmd_trans_huge(*vmf->pmd)) {3469 folio_unlock(folio);3470 folio_put(folio);3471 return true;3472 }3473 3474 if (pmd_none(*vmf->pmd) && folio_test_pmd_mappable(folio)) {3475 struct page *page = folio_file_page(folio, start);3476 vm_fault_t ret = do_set_pmd(vmf, page);3477 if (!ret) {3478 /* The page is mapped successfully, reference consumed. */3479 folio_unlock(folio);3480 return true;3481 }3482 }3483 3484 if (pmd_none(*vmf->pmd) && vmf->prealloc_pte)3485 pmd_install(mm, vmf->pmd, &vmf->prealloc_pte);3486 3487 return false;3488}3489 3490static HWJS_SUSPENDS struct folio *next_uptodate_folio(struct xa_state *xas,3491 struct address_space *mapping, pgoff_t end_pgoff)3492{3493 struct folio *folio = xas_next_entry(xas, end_pgoff);3494 unsigned long max_idx;3495 3496 do {3497 if (!folio)3498 return NULL;3499 if (xas_retry(xas, folio))3500 continue;3501 if (xa_is_value(folio))3502 continue;3503 if (folio_test_locked(folio))3504 continue;3505 if (!folio_try_get(folio))3506 continue;3507 /* Has the page moved or been split? */3508 if (unlikely(folio != xas_reload(xas)))3509 goto skip;3510 if (!folio_test_uptodate(folio) || folio_test_readahead(folio))3511 goto skip;3512 if (!folio_trylock(folio))3513 goto skip;3514 if (folio->mapping != mapping)3515 goto unlock;3516 if (!folio_test_uptodate(folio))3517 goto unlock;3518 max_idx = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);3519 if (xas->xa_index >= max_idx)3520 goto unlock;3521 return folio;3522unlock:3523 folio_unlock(folio);3524skip:3525 folio_put(folio);3526 } while ((folio = xas_next_entry(xas, end_pgoff)) != NULL);3527 3528 return NULL;3529}3530 3531/*3532 * Map page range [start_page, start_page + nr_pages) of folio.3533 * start_page is gotten from start by folio_page(folio, start)3534 */3535static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,3536 struct folio *folio, unsigned long start,3537 unsigned long addr, unsigned int nr_pages,3538 unsigned long *rss, unsigned int *mmap_miss)3539{3540 vm_fault_t ret = 0;3541 struct page *page = folio_page(folio, start);3542 unsigned int count = 0;3543 pte_t *old_ptep = vmf->pte;3544 3545 do {3546 if (PageHWPoison(page + count))3547 goto skip;3548 3549 /*3550 * If there are too many folios that are recently evicted3551 * in a file, they will probably continue to be evicted.3552 * In such situation, read-ahead is only a waste of IO.3553 * Don't decrease mmap_miss in this scenario to make sure3554 * we can stop read-ahead.3555 */3556 if (!folio_test_workingset(folio))3557 (*mmap_miss)++;3558 3559 /*3560 * NOTE: If there're PTE markers, we'll leave them to be3561 * handled in the specific fault path, and it'll prohibit the3562 * fault-around logic.3563 */3564 if (!pte_none(ptep_get(&vmf->pte[count])))3565 goto skip;3566 3567 count++;3568 continue;3569skip:3570 if (count) {3571 set_pte_range(vmf, folio, page, count, addr);3572 *rss += count;3573 folio_ref_add(folio, count);3574 if (in_range(vmf->address, addr, count * PAGE_SIZE))3575 ret = VM_FAULT_NOPAGE;3576 }3577 3578 count++;3579 page += count;3580 vmf->pte += count;3581 addr += count * PAGE_SIZE;3582 count = 0;3583 } while (--nr_pages > 0);3584 3585 if (count) {3586 set_pte_range(vmf, folio, page, count, addr);3587 *rss += count;3588 folio_ref_add(folio, count);3589 if (in_range(vmf->address, addr, count * PAGE_SIZE))3590 ret = VM_FAULT_NOPAGE;3591 }3592 3593 vmf->pte = old_ptep;3594 3595 return ret;3596}3597 3598static vm_fault_t filemap_map_order0_folio(struct vm_fault *vmf,3599 struct folio *folio, unsigned long addr,3600 unsigned long *rss, unsigned int *mmap_miss)3601{3602 vm_fault_t ret = 0;3603 struct page *page = &folio->page;3604 3605 if (PageHWPoison(page))3606 return ret;3607 3608 /* See comment of filemap_map_folio_range() */3609 if (!folio_test_workingset(folio))3610 (*mmap_miss)++;3611 3612 /*3613 * NOTE: If there're PTE markers, we'll leave them to be3614 * handled in the specific fault path, and it'll prohibit3615 * the fault-around logic.3616 */3617 if (!pte_none(ptep_get(vmf->pte)))3618 return ret;3619 3620 if (vmf->address == addr)3621 ret = VM_FAULT_NOPAGE;3622 3623 set_pte_range(vmf, folio, page, 1, addr);3624 (*rss)++;3625 folio_ref_inc(folio);3626 3627 return ret;3628}3629 3630vm_fault_t filemap_map_pages(struct vm_fault *vmf,3631 pgoff_t start_pgoff, pgoff_t end_pgoff)3632{3633 struct vm_area_struct *vma = vmf->vma;3634 struct file *file = vma->vm_file;3635 struct address_space *mapping = file->f_mapping;3636 pgoff_t file_end, last_pgoff = start_pgoff;3637 unsigned long addr;3638 XA_STATE(xas, &mapping->i_pages, start_pgoff);3639 struct folio *folio;3640 vm_fault_t ret = 0;3641 unsigned long rss = 0;3642 unsigned int nr_pages = 0, mmap_miss = 0, mmap_miss_saved, folio_type;3643 3644 rcu_read_lock();3645 folio = next_uptodate_folio(&xas, mapping, end_pgoff);3646 if (!folio)3647 goto out;3648 3649 if (filemap_map_pmd(vmf, folio, start_pgoff)) {3650 ret = VM_FAULT_NOPAGE;3651 goto out;3652 }3653 3654 addr = vma->vm_start + ((start_pgoff - vma->vm_pgoff) << PAGE_SHIFT);3655 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, addr, &vmf->ptl);3656 if (!vmf->pte) {3657 folio_unlock(folio);3658 folio_put(folio);3659 goto out;3660 }3661 3662 file_end = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE) - 1;3663 if (end_pgoff > file_end)3664 end_pgoff = file_end;3665 3666 folio_type = mm_counter_file(folio);3667 do {3668 unsigned long end;3669 3670 addr += (xas.xa_index - last_pgoff) << PAGE_SHIFT;3671 vmf->pte += xas.xa_index - last_pgoff;3672 last_pgoff = xas.xa_index;3673 end = folio_next_index(folio) - 1;3674 nr_pages = min(end, end_pgoff) - xas.xa_index + 1;3675 3676 if (!folio_test_large(folio))3677 ret |= filemap_map_order0_folio(vmf,3678 folio, addr, &rss, &mmap_miss);3679 else3680 ret |= filemap_map_folio_range(vmf, folio,3681 xas.xa_index - folio->index, addr,3682 nr_pages, &rss, &mmap_miss);3683 3684 folio_unlock(folio);3685 folio_put(folio);3686 } while ((folio = next_uptodate_folio(&xas, mapping, end_pgoff)) != NULL);3687 add_mm_counter(vma->vm_mm, folio_type, rss);3688 pte_unmap_unlock(vmf->pte, vmf->ptl);3689 trace_mm_filemap_map_pages(mapping, start_pgoff, end_pgoff);3690out:3691 rcu_read_unlock();3692 3693 mmap_miss_saved = READ_ONCE(file->f_ra.mmap_miss);3694 if (mmap_miss >= mmap_miss_saved)3695 WRITE_ONCE(file->f_ra.mmap_miss, 0);3696 else3697 WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss_saved - mmap_miss);3698 3699 return ret;3700}3701EXPORT_SYMBOL(filemap_map_pages);3702 3703vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf)3704{3705 struct address_space *mapping = vmf->vma->vm_file->f_mapping;3706 struct folio *folio = page_folio(vmf->page);3707 vm_fault_t ret = VM_FAULT_LOCKED;3708 3709 sb_start_pagefault(mapping->host->i_sb);3710 file_update_time(vmf->vma->vm_file);3711 folio_lock(folio);3712 if (folio->mapping != mapping) {3713 folio_unlock(folio);3714 ret = VM_FAULT_NOPAGE;3715 goto out;3716 }3717 /*3718 * We mark the folio dirty already here so that when freeze is in3719 * progress, we are guaranteed that writeback during freezing will3720 * see the dirty folio and writeprotect it again.3721 */3722 folio_mark_dirty(folio);3723 folio_wait_stable(folio);3724out:3725 sb_end_pagefault(mapping->host->i_sb);3726 return ret;3727}3728 3729const struct vm_operations_struct generic_file_vm_ops = {3730 .fault = filemap_fault,3731 .map_pages = filemap_map_pages,3732 .page_mkwrite = filemap_page_mkwrite,3733};3734 3735/* This is used for a general mmap of a disk file */3736 3737int generic_file_mmap(struct file *file, struct vm_area_struct *vma)3738{3739 struct address_space *mapping = file->f_mapping;3740 3741 if (!mapping->a_ops->read_folio)3742 return -ENOEXEC;3743 file_accessed(file);3744 vma->vm_ops = &generic_file_vm_ops;3745 return 0;3746}3747 3748/*3749 * This is for filesystems which do not implement ->writepage.3750 */3751int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)3752{3753 if (vma_is_shared_maywrite(vma))3754 return -EINVAL;3755 return generic_file_mmap(file, vma);3756}3757#else3758vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf)3759{3760 return VM_FAULT_SIGBUS;3761}3762int generic_file_mmap(struct file *file, struct vm_area_struct *vma)3763{3764 return -ENOSYS;3765}3766int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)3767{3768 return -ENOSYS;3769}3770#endif /* CONFIG_MMU */3771 3772EXPORT_SYMBOL(filemap_page_mkwrite);3773EXPORT_SYMBOL(generic_file_mmap);3774EXPORT_SYMBOL(generic_file_readonly_mmap);3775 3776static HWJS_SUSPENDS struct folio *do_read_cache_folio(struct address_space *mapping,3777 pgoff_t index, filler_t filler, struct file *file, gfp_t gfp)3778{3779 struct folio *folio;3780 int err;3781 3782 if (!filler)3783 filler = mapping->a_ops->read_folio;3784repeat:3785 folio = filemap_get_folio(mapping, index);3786 if (IS_ERR(folio)) {3787 folio = filemap_alloc_folio(gfp,3788 mapping_min_folio_order(mapping));3789 if (!folio)3790 return ERR_PTR(-ENOMEM);3791 index = mapping_align_index(mapping, index);3792 err = filemap_add_folio(mapping, folio, index, gfp);3793 if (unlikely(err)) {3794 folio_put(folio);3795 if (err == -EEXIST)3796 goto repeat;3797 /* Presumably ENOMEM for xarray node */3798 return ERR_PTR(err);3799 }3800 3801 goto filler;3802 }3803 if (folio_test_uptodate(folio))3804 goto out;3805 3806 if (!folio_trylock(folio)) {3807 folio_put_wait_locked(folio, TASK_UNINTERRUPTIBLE);3808 goto repeat;3809 }3810 3811 /* Folio was truncated from mapping */3812 if (!folio->mapping) {3813 folio_unlock(folio);3814 folio_put(folio);3815 goto repeat;3816 }3817 3818 /* Someone else locked and filled the page in a very small window */3819 if (folio_test_uptodate(folio)) {3820 folio_unlock(folio);3821 goto out;3822 }3823 3824filler:3825 err = filemap_read_folio(file, filler, folio);3826 if (err) {3827 folio_put(folio);3828 if (err == AOP_TRUNCATED_PAGE)3829 goto repeat;3830 return ERR_PTR(err);3831 }3832 3833out:3834 folio_mark_accessed(folio);3835 return folio;3836}3837 3838/**3839 * read_cache_folio - Read into page cache, fill it if needed.3840 * @mapping: The address_space to read from.3841 * @index: The index to read.3842 * @filler: Function to perform the read, or NULL to use aops->read_folio().3843 * @file: Passed to filler function, may be NULL if not required.3844 *3845 * Read one page into the page cache. If it succeeds, the folio returned3846 * will contain @index, but it may not be the first page of the folio.3847 *3848 * If the filler function returns an error, it will be returned to the3849 * caller.3850 *3851 * Context: May sleep. Expects mapping->invalidate_lock to be held.3852 * Return: An uptodate folio on success, ERR_PTR() on failure.3853 */3854struct folio *read_cache_folio(struct address_space *mapping, pgoff_t index,3855 filler_t filler, struct file *file)3856{3857 return do_read_cache_folio(mapping, index, filler, file,3858 mapping_gfp_mask(mapping));3859}3860EXPORT_SYMBOL(read_cache_folio);3861 3862/**3863 * mapping_read_folio_gfp - Read into page cache, using specified allocation flags.3864 * @mapping: The address_space for the folio.3865 * @index: The index that the allocated folio will contain.3866 * @gfp: The page allocator flags to use if allocating.3867 *3868 * This is the same as "read_cache_folio(mapping, index, NULL, NULL)", but with3869 * any new memory allocations done using the specified allocation flags.3870 *3871 * The most likely error from this function is EIO, but ENOMEM is3872 * possible and so is EINTR. If ->read_folio returns another error,3873 * that will be returned to the caller.3874 *3875 * The function expects mapping->invalidate_lock to be already held.3876 *3877 * Return: Uptodate folio on success, ERR_PTR() on failure.3878 */3879struct folio *mapping_read_folio_gfp(struct address_space *mapping,3880 pgoff_t index, gfp_t gfp)3881{3882 return do_read_cache_folio(mapping, index, NULL, NULL, gfp);3883}3884EXPORT_SYMBOL(mapping_read_folio_gfp);3885 3886static HWJS_SUSPENDS struct page *do_read_cache_page(struct address_space *mapping,3887 pgoff_t index, filler_t *filler, struct file *file, gfp_t gfp)3888{3889 struct folio *folio;3890 3891 folio = do_read_cache_folio(mapping, index, filler, file, gfp);3892 if (IS_ERR(folio))3893 return &folio->page;3894 return folio_file_page(folio, index);3895}3896 3897struct page *read_cache_page(struct address_space *mapping,3898 pgoff_t index, filler_t *filler, struct file *file)3899{3900 return do_read_cache_page(mapping, index, filler, file,3901 mapping_gfp_mask(mapping));3902}3903EXPORT_SYMBOL(read_cache_page);3904 3905/**3906 * read_cache_page_gfp - read into page cache, using specified page allocation flags.3907 * @mapping: the page's address_space3908 * @index: the page index3909 * @gfp: the page allocator flags to use if allocating3910 *3911 * This is the same as "read_mapping_page(mapping, index, NULL)", but with3912 * any new page allocations done using the specified allocation flags.3913 *3914 * If the page does not get brought uptodate, return -EIO.3915 *3916 * The function expects mapping->invalidate_lock to be already held.3917 *3918 * Return: up to date page on success, ERR_PTR() on failure.3919 */3920struct page *read_cache_page_gfp(struct address_space *mapping,3921 pgoff_t index,3922 gfp_t gfp)3923{3924 return do_read_cache_page(mapping, index, NULL, NULL, gfp);3925}3926EXPORT_SYMBOL(read_cache_page_gfp);3927 3928/*3929 * Warn about a page cache invalidation failure during a direct I/O write.3930 */3931static void dio_warn_stale_pagecache(struct file *filp)3932{3933 static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST);3934 char pathname[128];3935 char *path;3936 3937 errseq_set(&filp->f_mapping->wb_err, -EIO);3938 if (__ratelimit(&_rs)) {3939 path = file_path(filp, pathname, sizeof(pathname));3940 if (IS_ERR(path))3941 path = "(unknown)";3942 pr_crit("Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O!\n");3943 pr_crit("File: %s PID: %d Comm: %.20s\n", path, current->pid,3944 current->comm);3945 }3946}3947 3948void kiocb_invalidate_post_direct_write(struct kiocb *iocb, size_t count)3949{3950 struct address_space *mapping = iocb->ki_filp->f_mapping;3951 3952 if (mapping->nrpages &&3953 invalidate_inode_pages2_range(mapping,3954 iocb->ki_pos >> PAGE_SHIFT,3955 (iocb->ki_pos + count - 1) >> PAGE_SHIFT))3956 dio_warn_stale_pagecache(iocb->ki_filp);3957}3958 3959ssize_t3960generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)3961{3962 struct address_space *mapping = iocb->ki_filp->f_mapping;3963 size_t write_len = iov_iter_count(from);3964 ssize_t written;3965 3966 /*3967 * If a page can not be invalidated, return 0 to fall back3968 * to buffered write.3969 */3970 written = kiocb_invalidate_pages(iocb, write_len);3971 if (written) {3972 if (written == -EBUSY)3973 return 0;3974 return written;3975 }3976 3977 written = mapping->a_ops->direct_IO(iocb, from);3978 3979 /*3980 * Finally, try again to invalidate clean pages which might have been3981 * cached by non-direct readahead, or faulted in by get_user_pages()3982 * if the source of the write was an mmap'ed region of the file3983 * we're writing. Either one is a pretty crazy thing to do,3984 * so we don't support it 100%. If this invalidation3985 * fails, tough, the write still worked...3986 *3987 * Most of the time we do not need this since dio_complete() will do3988 * the invalidation for us. However there are some file systems that3989 * do not end up with dio_complete() being called, so let's not break3990 * them by removing it completely.3991 *3992 * Noticeable example is a blkdev_direct_IO().3993 *3994 * Skip invalidation for async writes or if mapping has no pages.3995 */3996 if (written > 0) {3997 struct inode *inode = mapping->host;3998 loff_t pos = iocb->ki_pos;3999 4000 kiocb_invalidate_post_direct_write(iocb, written);4001 pos += written;4002 write_len -= written;4003 if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {4004 i_size_write(inode, pos);4005 mark_inode_dirty(inode);4006 }4007 iocb->ki_pos = pos;4008 }4009 if (written != -EIOCBQUEUED)4010 iov_iter_revert(from, write_len - iov_iter_count(from));4011 return written;4012}4013EXPORT_SYMBOL(generic_file_direct_write);4014 4015ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i)4016{4017 struct file *file = iocb->ki_filp;4018 loff_t pos = iocb->ki_pos;4019 struct address_space *mapping = file->f_mapping;4020 const struct address_space_operations *a_ops = mapping->a_ops;4021 size_t chunk = mapping_max_folio_size(mapping);4022 long status = 0;4023 ssize_t written = 0;4024 4025 do {4026 struct folio *folio;4027 size_t offset; /* Offset into folio */4028 size_t bytes; /* Bytes to write to folio */4029 size_t copied; /* Bytes copied from user */4030 void *fsdata = NULL;4031 4032 bytes = iov_iter_count(i);4033retry:4034 offset = pos & (chunk - 1);4035 bytes = min(chunk - offset, bytes);4036 balance_dirty_pages_ratelimited(mapping);4037 4038 /*4039 * Bring in the user page that we will copy from _first_.4040 * Otherwise there's a nasty deadlock on copying from the4041 * same page as we're writing to, without it being marked4042 * up-to-date.4043 */4044 if (unlikely(fault_in_iov_iter_readable(i, bytes) == bytes)) {4045 status = -EFAULT;4046 break;4047 }4048 4049 if (fatal_signal_pending(current)) {4050 status = -EINTR;4051 break;4052 }4053 4054 status = a_ops->write_begin(file, mapping, pos, bytes,4055 &folio, &fsdata);4056 if (unlikely(status < 0))4057 break;4058 4059 offset = offset_in_folio(folio, pos);4060 if (bytes > folio_size(folio) - offset)4061 bytes = folio_size(folio) - offset;4062 4063 if (mapping_writably_mapped(mapping))4064 flush_dcache_folio(folio);4065 4066 copied = copy_folio_from_iter_atomic(folio, offset, bytes, i);4067 flush_dcache_folio(folio);4068 4069 status = a_ops->write_end(file, mapping, pos, bytes, copied,4070 folio, fsdata);4071 if (unlikely(status != copied)) {4072 iov_iter_revert(i, copied - max(status, 0L));4073 if (unlikely(status < 0))4074 break;4075 }4076 cond_resched();4077 4078 if (unlikely(status == 0)) {4079 /*4080 * A short copy made ->write_end() reject the4081 * thing entirely. Might be memory poisoning4082 * halfway through, might be a race with munmap,4083 * might be severe memory pressure.4084 */4085 if (chunk > PAGE_SIZE)4086 chunk /= 2;4087 if (copied) {4088 bytes = copied;4089 goto retry;4090 }4091 } else {4092 pos += status;4093 written += status;4094 }4095 } while (iov_iter_count(i));4096 4097 if (!written)4098 return status;4099 iocb->ki_pos += written;4100 return written;4101}4102EXPORT_SYMBOL(generic_perform_write);4103 4104/**4105 * __generic_file_write_iter - write data to a file4106 * @iocb: IO state structure (file, offset, etc.)4107 * @from: iov_iter with data to write4108 *4109 * This function does all the work needed for actually writing data to a4110 * file. It does all basic checks, removes SUID from the file, updates4111 * modification times and calls proper subroutines depending on whether we4112 * do direct IO or a standard buffered write.4113 *4114 * It expects i_rwsem to be grabbed unless we work on a block device or similar4115 * object which does not need locking at all.4116 *4117 * This function does *not* take care of syncing data in case of O_SYNC write.4118 * A caller has to handle it. This is mainly due to the fact that we want to4119 * avoid syncing under i_rwsem.4120 *4121 * Return:4122 * * number of bytes written, even for truncated writes4123 * * negative error code if no data has been written at all4124 */4125ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)4126{4127 struct file *file = iocb->ki_filp;4128 struct address_space *mapping = file->f_mapping;4129 struct inode *inode = mapping->host;4130 ssize_t ret;4131 4132 ret = file_remove_privs(file);4133 if (ret)4134 return ret;4135 4136 ret = file_update_time(file);4137 if (ret)4138 return ret;4139 4140 if (iocb->ki_flags & IOCB_DIRECT) {4141 ret = generic_file_direct_write(iocb, from);4142 /*4143 * If the write stopped short of completing, fall back to4144 * buffered writes. Some filesystems do this for writes to4145 * holes, for example. For DAX files, a buffered write will4146 * not succeed (even if it did, DAX does not handle dirty4147 * page-cache pages correctly).4148 */4149 if (ret < 0 || !iov_iter_count(from) || IS_DAX(inode))4150 return ret;4151 return direct_write_fallback(iocb, from, ret,4152 generic_perform_write(iocb, from));4153 }4154 4155 return generic_perform_write(iocb, from);4156}4157EXPORT_SYMBOL(__generic_file_write_iter);4158 4159/**4160 * generic_file_write_iter - write data to a file4161 * @iocb: IO state structure4162 * @from: iov_iter with data to write4163 *4164 * This is a wrapper around __generic_file_write_iter() to be used by most4165 * filesystems. It takes care of syncing the file in case of O_SYNC file4166 * and acquires i_rwsem as needed.4167 * Return:4168 * * negative error code if no data has been written at all of4169 * vfs_fsync_range() failed for a synchronous write4170 * * number of bytes written, even for truncated writes4171 */4172ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)4173{4174 struct file *file = iocb->ki_filp;4175 struct inode *inode = file->f_mapping->host;4176 ssize_t ret;4177 4178 inode_lock(inode);4179 ret = generic_write_checks(iocb, from);4180 if (ret > 0)4181 ret = __generic_file_write_iter(iocb, from);4182 inode_unlock(inode);4183 4184 if (ret > 0)4185 ret = generic_write_sync(iocb, ret);4186 return ret;4187}4188EXPORT_SYMBOL(generic_file_write_iter);4189 4190/**4191 * filemap_release_folio() - Release fs-specific metadata on a folio.4192 * @folio: The folio which the kernel is trying to free.4193 * @gfp: Memory allocation flags (and I/O mode).4194 *4195 * The address_space is trying to release any data attached to a folio4196 * (presumably at folio->private).4197 *4198 * This will also be called if the private_2 flag is set on a page,4199 * indicating that the folio has other metadata associated with it.4200 *4201 * The @gfp argument specifies whether I/O may be performed to release4202 * this page (__GFP_IO), and whether the call may block4203 * (__GFP_RECLAIM & __GFP_FS).4204 *4205 * Return: %true if the release was successful, otherwise %false.4206 */4207bool filemap_release_folio(struct folio *folio, gfp_t gfp)4208{4209 struct address_space * const mapping = folio->mapping;4210 4211 BUG_ON(!folio_test_locked(folio));4212 if (!folio_needs_release(folio))4213 return true;4214 if (folio_test_writeback(folio))4215 return false;4216 4217 if (mapping && mapping->a_ops->release_folio)4218 return mapping->a_ops->release_folio(folio, gfp);4219 return try_to_free_buffers(folio);4220}4221EXPORT_SYMBOL(filemap_release_folio);4222 4223/**4224 * filemap_invalidate_inode - Invalidate/forcibly write back a range of an inode's pagecache4225 * @inode: The inode to flush4226 * @flush: Set to write back rather than simply invalidate.4227 * @start: First byte to in range.4228 * @end: Last byte in range (inclusive), or LLONG_MAX for everything from start4229 * onwards.4230 *4231 * Invalidate all the folios on an inode that contribute to the specified4232 * range, possibly writing them back first. Whilst the operation is4233 * undertaken, the invalidate lock is held to prevent new folios from being4234 * installed.4235 */4236int filemap_invalidate_inode(struct inode *inode, bool flush,4237 loff_t start, loff_t end)4238{4239 struct address_space *mapping = inode->i_mapping;4240 pgoff_t first = start >> PAGE_SHIFT;4241 pgoff_t last = end >> PAGE_SHIFT;4242 pgoff_t nr = end == LLONG_MAX ? ULONG_MAX : last - first + 1;4243 4244 if (!mapping || !mapping->nrpages || end < start)4245 goto out;4246 4247 /* Prevent new folios from being added to the inode. */4248 filemap_invalidate_lock(mapping);4249 4250 if (!mapping->nrpages)4251 goto unlock;4252 4253 unmap_mapping_pages(mapping, first, nr, false);4254 4255 /* Write back the data if we're asked to. */4256 if (flush) {4257 struct writeback_control wbc = {4258 .sync_mode = WB_SYNC_ALL,4259 .nr_to_write = LONG_MAX,4260 .range_start = start,4261 .range_end = end,4262 };4263 4264 filemap_fdatawrite_wbc(mapping, &wbc);4265 }4266 4267 /* Wait for writeback to complete on all folios and discard. */4268 invalidate_inode_pages2_range(mapping, start / PAGE_SIZE, end / PAGE_SIZE);4269 4270unlock:4271 filemap_invalidate_unlock(mapping);4272out:4273 return filemap_check_errors(mapping);4274}4275EXPORT_SYMBOL_GPL(filemap_invalidate_inode);4276 4277#ifdef CONFIG_CACHESTAT_SYSCALL4278/**4279 * filemap_cachestat() - compute the page cache statistics of a mapping4280 * @mapping: The mapping to compute the statistics for.4281 * @first_index: The starting page cache index.4282 * @last_index: The final page index (inclusive).4283 * @cs: the cachestat struct to write the result to.4284 *4285 * This will query the page cache statistics of a mapping in the4286 * page range of [first_index, last_index] (inclusive). The statistics4287 * queried include: number of dirty pages, number of pages marked for4288 * writeback, and the number of (recently) evicted pages.4289 */4290static void filemap_cachestat(struct address_space *mapping,4291 pgoff_t first_index, pgoff_t last_index, struct cachestat *cs)4292{4293 XA_STATE(xas, &mapping->i_pages, first_index);4294 struct folio *folio;4295 4296 /* Flush stats (and potentially sleep) outside the RCU read section. */4297 mem_cgroup_flush_stats_ratelimited(NULL);4298 4299 rcu_read_lock();4300 xas_for_each(&xas, folio, last_index) {4301 int order;4302 unsigned long nr_pages;4303 pgoff_t folio_first_index, folio_last_index;4304 4305 /*4306 * Don't deref the folio. It is not pinned, and might4307 * get freed (and reused) underneath us.4308 *4309 * We *could* pin it, but that would be expensive for4310 * what should be a fast and lightweight syscall.4311 *4312 * Instead, derive all information of interest from4313 * the rcu-protected xarray.4314 */4315 4316 if (xas_retry(&xas, folio))4317 continue;4318 4319 order = xas_get_order(&xas);4320 nr_pages = 1 << order;4321 folio_first_index = round_down(xas.xa_index, 1 << order);4322 folio_last_index = folio_first_index + nr_pages - 1;4323 4324 /* Folios might straddle the range boundaries, only count covered pages */4325 if (folio_first_index < first_index)4326 nr_pages -= first_index - folio_first_index;4327 4328 if (folio_last_index > last_index)4329 nr_pages -= folio_last_index - last_index;4330 4331 if (xa_is_value(folio)) {4332 /* page is evicted */4333 void *shadow = (void *)folio;4334 bool workingset; /* not used */4335 4336 cs->nr_evicted += nr_pages;4337 4338#ifdef CONFIG_SWAP /* implies CONFIG_MMU */4339 if (shmem_mapping(mapping)) {4340 /* shmem file - in swap cache */4341 swp_entry_t swp = radix_to_swp_entry(folio);4342 4343 /* swapin error results in poisoned entry */4344 if (non_swap_entry(swp))4345 goto resched;4346 4347 /*4348 * Getting a swap entry from the shmem4349 * inode means we beat4350 * shmem_unuse(). rcu_read_lock()4351 * ensures swapoff waits for us before4352 * freeing the swapper space. However,4353 * we can race with swapping and4354 * invalidation, so there might not be4355 * a shadow in the swapcache (yet).4356 */4357 shadow = get_shadow_from_swap_cache(swp);4358 if (!shadow)4359 goto resched;4360 }4361#endif4362 if (workingset_test_recent(shadow, true, &workingset, false))4363 cs->nr_recently_evicted += nr_pages;4364 4365 goto resched;4366 }4367 4368 /* page is in cache */4369 cs->nr_cache += nr_pages;4370 4371 if (xas_get_mark(&xas, PAGECACHE_TAG_DIRTY))4372 cs->nr_dirty += nr_pages;4373 4374 if (xas_get_mark(&xas, PAGECACHE_TAG_WRITEBACK))4375 cs->nr_writeback += nr_pages;4376 4377resched:4378 if (need_resched()) {4379 xas_pause(&xas);4380 cond_resched_rcu();4381 }4382 }4383 rcu_read_unlock();4384}4385 4386/*4387 * The cachestat(2) system call.4388 *4389 * cachestat() returns the page cache statistics of a file in the4390 * bytes range specified by `off` and `len`: number of cached pages,4391 * number of dirty pages, number of pages marked for writeback,4392 * number of evicted pages, and number of recently evicted pages.4393 *4394 * An evicted page is a page that is previously in the page cache4395 * but has been evicted since. A page is recently evicted if its last4396 * eviction was recent enough that its reentry to the cache would4397 * indicate that it is actively being used by the system, and that4398 * there is memory pressure on the system.4399 *4400 * `off` and `len` must be non-negative integers. If `len` > 0,4401 * the queried range is [`off`, `off` + `len`]. If `len` == 0,4402 * we will query in the range from `off` to the end of the file.4403 *4404 * The `flags` argument is unused for now, but is included for future4405 * extensibility. User should pass 0 (i.e no flag specified).4406 *4407 * Currently, hugetlbfs is not supported.4408 *4409 * Because the status of a page can change after cachestat() checks it4410 * but before it returns to the application, the returned values may4411 * contain stale information.4412 *4413 * return values:4414 * zero - success4415 * -EFAULT - cstat or cstat_range points to an illegal address4416 * -EINVAL - invalid flags4417 * -EBADF - invalid file descriptor4418 * -EOPNOTSUPP - file descriptor is of a hugetlbfs file4419 */4420SYSCALL_DEFINE4(cachestat, unsigned int, fd,4421 struct cachestat_range __user *, cstat_range,4422 struct cachestat __user *, cstat, unsigned int, flags)4423{4424 struct fd f = fdget(fd);4425 struct address_space *mapping;4426 struct cachestat_range csr;4427 struct cachestat cs;4428 pgoff_t first_index, last_index;4429 4430 if (!fd_file(f))4431 return -EBADF;4432 4433 if (copy_from_user(&csr, cstat_range,4434 sizeof(struct cachestat_range))) {4435 fdput(f);4436 return -EFAULT;4437 }4438 4439 /* hugetlbfs is not supported */4440 if (is_file_hugepages(fd_file(f))) {4441 fdput(f);4442 return -EOPNOTSUPP;4443 }4444 4445 if (flags != 0) {4446 fdput(f);4447 return -EINVAL;4448 }4449 4450 first_index = csr.off >> PAGE_SHIFT;4451 last_index =4452 csr.len == 0 ? ULONG_MAX : (csr.off + csr.len - 1) >> PAGE_SHIFT;4453 memset(&cs, 0, sizeof(struct cachestat));4454 mapping = fd_file(f)->f_mapping;4455 filemap_cachestat(mapping, first_index, last_index, &cs);4456 fdput(f);4457 4458 if (copy_to_user(cstat, &cs, sizeof(struct cachestat)))4459 return -EFAULT;4460 4461 return 0;4462}4463#endif /* CONFIG_CACHESTAT_SYSCALL */4464