blob: 1358cb061fd65ddaf7c72831de5f7ac834cbce00 [file] [log] [blame]
Thomas Gleixner457c8992019-05-19 13:08:55 +01001// SPDX-License-Identifier: GPL-2.0-only
Linus Torvalds1da177e2005-04-16 15:20:36 -07002/*
3 * linux/mm/filemap.c
4 *
5 * Copyright (C) 1994-1999 Linus Torvalds
6 */
7
8/*
9 * This file handles the generic file mmap semantics used by
10 * most "normal" filesystems (but you don't /have/ to use this:
11 * the NFS filesystem used to do this differently, for example)
12 */
Paul Gortmakerb95f1b312011-10-16 02:01:52 -040013#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/compiler.h>
Ross Zwislerf9fe48b2016-01-22 15:10:40 -080015#include <linux/dax.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070016#include <linux/fs.h>
Ingo Molnar3f07c012017-02-08 18:51:30 +010017#include <linux/sched/signal.h>
Hiro Yoshiokac22ce142006-06-23 02:04:16 -070018#include <linux/uaccess.h>
Randy.Dunlapc59ede72006-01-11 12:17:46 -080019#include <linux/capability.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070020#include <linux/kernel_stat.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090021#include <linux/gfp.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070022#include <linux/mm.h>
23#include <linux/swap.h>
24#include <linux/mman.h>
25#include <linux/pagemap.h>
26#include <linux/file.h>
27#include <linux/uio.h>
Josef Bacikcfcbfb12019-05-13 17:21:04 -070028#include <linux/error-injection.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070029#include <linux/hash.h>
30#include <linux/writeback.h>
Linus Torvalds53253382007-10-18 14:47:32 -070031#include <linux/backing-dev.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070032#include <linux/pagevec.h>
33#include <linux/blkdev.h>
34#include <linux/security.h>
Paul Jackson44110fe2006-03-24 03:16:04 -080035#include <linux/cpuset.h>
Johannes Weiner00501b52014-08-08 14:19:20 -070036#include <linux/hugetlb.h>
Balbir Singh8a9f3cc2008-02-07 00:13:53 -080037#include <linux/memcontrol.h>
Dan Magenheimerc515e1f2011-05-26 10:01:43 -060038#include <linux/cleancache.h>
Mel Gormanc7df8ad2017-11-15 17:37:41 -080039#include <linux/shmem_fs.h>
Kirill A. Shutemovf1820362014-04-07 15:37:19 -070040#include <linux/rmap.h>
Johannes Weinerb1d29ba2018-10-26 15:06:08 -070041#include <linux/delayacct.h>
Johannes Weinereb414682018-10-26 15:06:27 -070042#include <linux/psi.h>
Ben Dooksd0e6a582019-10-18 20:20:20 -070043#include <linux/ramfs.h>
Yang Shib9306a72020-08-06 23:19:55 -070044#include <linux/page_idle.h>
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +030045#include <asm/pgalloc.h>
Will Deaconde591a82021-02-10 11:15:11 +000046#include <asm/tlbflush.h>
Nick Piggin0f8053a2006-03-22 00:08:33 -080047#include "internal.h"
48
Robert Jarzmikfe0bfaa2013-04-29 15:06:10 -070049#define CREATE_TRACE_POINTS
50#include <trace/events/filemap.h>
51
Linus Torvalds1da177e2005-04-16 15:20:36 -070052/*
Linus Torvalds1da177e2005-04-16 15:20:36 -070053 * FIXME: remove all knowledge of the buffer layer from the core VM
54 */
Jan Kara148f9482009-08-17 19:52:36 +020055#include <linux/buffer_head.h> /* for try_to_free_buffers */
Linus Torvalds1da177e2005-04-16 15:20:36 -070056
Linus Torvalds1da177e2005-04-16 15:20:36 -070057#include <asm/mman.h>
58
59/*
60 * Shared mappings implemented 30.11.1994. It's not fully working yet,
61 * though.
62 *
63 * Shared mappings now work. 15.8.1995 Bruno.
64 *
65 * finished 'unifying' the page and buffer cache and SMP-threaded the
66 * page-cache, 21.05.1999, Ingo Molnar <mingo@redhat.com>
67 *
68 * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <andrea@suse.de>
69 */
70
71/*
72 * Lock ordering:
73 *
Davidlohr Buesoc8c06ef2014-12-12 16:54:24 -080074 * ->i_mmap_rwsem (truncate_pagecache)
Linus Torvalds1da177e2005-04-16 15:20:36 -070075 * ->private_lock (__free_pte->__set_page_dirty_buffers)
Hugh Dickins5d337b92005-09-03 15:54:41 -070076 * ->swap_lock (exclusive_swap_page, others)
Matthew Wilcoxb93b0162018-04-10 16:36:56 -070077 * ->i_pages lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070078 *
Jes Sorensen1b1dcc12006-01-09 15:59:24 -080079 * ->i_mutex
Davidlohr Buesoc8c06ef2014-12-12 16:54:24 -080080 * ->i_mmap_rwsem (truncate->unmap_mapping_range)
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 *
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -070082 * ->mmap_lock
Davidlohr Buesoc8c06ef2014-12-12 16:54:24 -080083 * ->i_mmap_rwsem
Hugh Dickinsb8072f02005-10-29 18:16:41 -070084 * ->page_table_lock or pte_lock (various, mainly in memory.c)
Matthew Wilcoxb93b0162018-04-10 16:36:56 -070085 * ->i_pages lock (arch-dependent flush_dcache_mmap_lock)
Linus Torvalds1da177e2005-04-16 15:20:36 -070086 *
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -070087 * ->mmap_lock
Linus Torvalds1da177e2005-04-16 15:20:36 -070088 * ->lock_page (access_process_vm)
89 *
Al Viroccad2362014-02-11 22:36:48 -050090 * ->i_mutex (generic_perform_write)
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -070091 * ->mmap_lock (fault_in_pages_readable->do_page_fault)
Linus Torvalds1da177e2005-04-16 15:20:36 -070092 *
Christoph Hellwigf758eea2011-04-21 18:19:44 -060093 * bdi->wb.list_lock
Dave Chinnera66979a2011-03-22 22:23:41 +110094 * sb_lock (fs/fs-writeback.c)
Matthew Wilcoxb93b0162018-04-10 16:36:56 -070095 * ->i_pages lock (__sync_single_inode)
Linus Torvalds1da177e2005-04-16 15:20:36 -070096 *
Davidlohr Buesoc8c06ef2014-12-12 16:54:24 -080097 * ->i_mmap_rwsem
Linus Torvalds1da177e2005-04-16 15:20:36 -070098 * ->anon_vma.lock (vma_adjust)
99 *
100 * ->anon_vma.lock
Hugh Dickinsb8072f02005-10-29 18:16:41 -0700101 * ->page_table_lock or pte_lock (anon_vma_prepare and various)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700102 *
Hugh Dickinsb8072f02005-10-29 18:16:41 -0700103 * ->page_table_lock or pte_lock
Hugh Dickins5d337b92005-09-03 15:54:41 -0700104 * ->swap_lock (try_to_unmap_one)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700105 * ->private_lock (try_to_unmap_one)
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700106 * ->i_pages lock (try_to_unmap_one)
Hugh Dickins15b44732020-12-15 14:21:31 -0800107 * ->lruvec->lru_lock (follow_page->mark_page_accessed)
108 * ->lruvec->lru_lock (check_pte_range->isolate_lru_page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700109 * ->private_lock (page_remove_rmap->set_page_dirty)
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700110 * ->i_pages lock (page_remove_rmap->set_page_dirty)
Christoph Hellwigf758eea2011-04-21 18:19:44 -0600111 * bdi.wb->list_lock (page_remove_rmap->set_page_dirty)
Dave Chinner250df6e2011-03-22 22:23:36 +1100112 * ->inode->i_lock (page_remove_rmap->set_page_dirty)
Johannes Weiner81f8c3a2016-03-15 14:57:04 -0700113 * ->memcg->move_lock (page_remove_rmap->lock_page_memcg)
Christoph Hellwigf758eea2011-04-21 18:19:44 -0600114 * bdi.wb->list_lock (zap_pte_range->set_page_dirty)
Dave Chinner250df6e2011-03-22 22:23:36 +1100115 * ->inode->i_lock (zap_pte_range->set_page_dirty)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700116 * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
117 *
Davidlohr Buesoc8c06ef2014-12-12 16:54:24 -0800118 * ->i_mmap_rwsem
Andi Kleen9a3c5312012-03-21 16:34:09 -0700119 * ->tasklist_lock (memory_failure, collect_procs_ao)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 */
121
Matthew Wilcox5c024e6a2017-11-21 09:17:59 -0500122static void page_cache_delete(struct address_space *mapping,
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700123 struct page *page, void *shadow)
124{
Matthew Wilcox5c024e6a2017-11-21 09:17:59 -0500125 XA_STATE(xas, &mapping->i_pages, page->index);
126 unsigned int nr = 1;
Kirill A. Shutemovc70b6472016-12-12 16:43:17 -0800127
Matthew Wilcox5c024e6a2017-11-21 09:17:59 -0500128 mapping_set_update(&xas, mapping);
129
130 /* hugetlb pages are represented by a single entry in the xarray */
131 if (!PageHuge(page)) {
132 xas_set_order(&xas, page->index, compound_order(page));
Matthew Wilcox (Oracle)d8c65462019-09-23 15:34:30 -0700133 nr = compound_nr(page);
Matthew Wilcox5c024e6a2017-11-21 09:17:59 -0500134 }
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700135
Kirill A. Shutemov83929372016-07-26 15:26:04 -0700136 VM_BUG_ON_PAGE(!PageLocked(page), page);
137 VM_BUG_ON_PAGE(PageTail(page), page);
138 VM_BUG_ON_PAGE(nr != 1 && shadow, page);
Johannes Weiner449dd692014-04-03 14:47:56 -0700139
Matthew Wilcox5c024e6a2017-11-21 09:17:59 -0500140 xas_store(&xas, shadow);
141 xas_init_marks(&xas);
Johannes Weinerd3798ae2016-10-04 22:02:08 +0200142
Jan Kara23006382017-11-15 17:37:26 -0800143 page->mapping = NULL;
144 /* Leave page->index set: truncation lookup relies upon it */
145
Johannes Weinerd3798ae2016-10-04 22:02:08 +0200146 if (shadow) {
147 mapping->nrexceptional += nr;
148 /*
149 * Make sure the nrexceptional update is committed before
150 * the nrpages update so that final truncate racing
151 * with reclaim does not see both counters 0 at the
152 * same time and miss a shadow entry.
153 */
154 smp_wmb();
155 }
156 mapping->nrpages -= nr;
Johannes Weiner91b0abe2014-04-03 14:47:49 -0700157}
158
Jan Kara5ecc4d82017-11-15 17:37:29 -0800159static void unaccount_page_cache_page(struct address_space *mapping,
160 struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161{
Jan Kara5ecc4d82017-11-15 17:37:29 -0800162 int nr;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700163
Dan Magenheimerc515e1f2011-05-26 10:01:43 -0600164 /*
165 * if we're uptodate, flush out into the cleancache, otherwise
166 * invalidate any existing cleancache entries. We can't leave
167 * stale data around in the cleancache once our page is gone
168 */
169 if (PageUptodate(page) && PageMappedToDisk(page))
170 cleancache_put_page(page);
171 else
Dan Magenheimer31677602011-09-21 11:56:28 -0400172 cleancache_invalidate_page(mapping, page);
Dan Magenheimerc515e1f2011-05-26 10:01:43 -0600173
Kirill A. Shutemov83929372016-07-26 15:26:04 -0700174 VM_BUG_ON_PAGE(PageTail(page), page);
Hugh Dickins06b241f2016-03-09 14:08:07 -0800175 VM_BUG_ON_PAGE(page_mapped(page), page);
176 if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(page_mapped(page))) {
177 int mapcount;
178
179 pr_alert("BUG: Bad page cache in process %s pfn:%05lx\n",
180 current->comm, page_to_pfn(page));
181 dump_page(page, "still mapped when deleted");
182 dump_stack();
183 add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
184
185 mapcount = page_mapcount(page);
186 if (mapping_exiting(mapping) &&
187 page_count(page) >= mapcount + 2) {
188 /*
189 * All vmas have already been torn down, so it's
190 * a good bet that actually the page is unmapped,
191 * and we'd prefer not to leak it: if we're wrong,
192 * some other bad page check should catch it later.
193 */
194 page_mapcount_reset(page);
Joonsoo Kim6d061f92016-05-19 17:10:46 -0700195 page_ref_sub(page, mapcount);
Hugh Dickins06b241f2016-03-09 14:08:07 -0800196 }
197 }
198
Jan Kara76253fb2017-11-15 17:37:22 -0800199 /* hugetlb pages do not participate in page cache accounting. */
Jan Kara5ecc4d82017-11-15 17:37:29 -0800200 if (PageHuge(page))
201 return;
Jan Kara76253fb2017-11-15 17:37:22 -0800202
Matthew Wilcox (Oracle)6c357842020-08-14 17:30:37 -0700203 nr = thp_nr_pages(page);
Jan Kara5ecc4d82017-11-15 17:37:29 -0800204
Johannes Weiner0d1c2072020-06-03 16:01:54 -0700205 __mod_lruvec_page_state(page, NR_FILE_PAGES, -nr);
Jan Kara5ecc4d82017-11-15 17:37:29 -0800206 if (PageSwapBacked(page)) {
Johannes Weiner0d1c2072020-06-03 16:01:54 -0700207 __mod_lruvec_page_state(page, NR_SHMEM, -nr);
Jan Kara5ecc4d82017-11-15 17:37:29 -0800208 if (PageTransHuge(page))
Johannes Weinerb8eddff2020-12-14 19:06:20 -0800209 __dec_lruvec_page_state(page, NR_SHMEM_THPS);
Song Liu99cb0db2019-09-23 15:38:00 -0700210 } else if (PageTransHuge(page)) {
Johannes Weinerb8eddff2020-12-14 19:06:20 -0800211 __dec_lruvec_page_state(page, NR_FILE_THPS);
Song Liu09d91cd2019-09-23 15:38:03 -0700212 filemap_nr_thps_dec(mapping);
Jan Kara76253fb2017-11-15 17:37:22 -0800213 }
Jan Kara5ecc4d82017-11-15 17:37:29 -0800214
215 /*
216 * At this point page must be either written or cleaned by
217 * truncate. Dirty page here signals a bug and loss of
218 * unwritten data.
219 *
220 * This fixes dirty accounting after removing the page entirely
221 * but leaves PageDirty set: it has no effect for truncated
222 * page and anyway will be cleared before returning page into
223 * buddy allocator.
224 */
225 if (WARN_ON_ONCE(PageDirty(page)))
226 account_page_cleaned(page, mapping, inode_to_wb(mapping->host));
227}
228
229/*
230 * Delete a page from the page cache and free it. Caller has to make
231 * sure the page is locked and that nobody else uses it - or that usage
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700232 * is safe. The caller must hold the i_pages lock.
Jan Kara5ecc4d82017-11-15 17:37:29 -0800233 */
234void __delete_from_page_cache(struct page *page, void *shadow)
235{
236 struct address_space *mapping = page->mapping;
237
238 trace_mm_filemap_delete_from_page_cache(page);
239
240 unaccount_page_cache_page(mapping, page);
Matthew Wilcox5c024e6a2017-11-21 09:17:59 -0500241 page_cache_delete(mapping, page, shadow);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700242}
243
Jan Kara59c66c52017-11-15 17:37:18 -0800244static void page_cache_free_page(struct address_space *mapping,
245 struct page *page)
246{
247 void (*freepage)(struct page *);
248
249 freepage = mapping->a_ops->freepage;
250 if (freepage)
251 freepage(page);
252
253 if (PageTransHuge(page) && !PageHuge(page)) {
Matthew Wilcox (Oracle)887b22c2020-10-15 20:05:23 -0700254 page_ref_sub(page, thp_nr_pages(page));
Jan Kara59c66c52017-11-15 17:37:18 -0800255 VM_BUG_ON_PAGE(page_count(page) <= 0, page);
256 } else {
257 put_page(page);
258 }
259}
260
Minchan Kim702cfbf2011-03-22 16:32:43 -0700261/**
262 * delete_from_page_cache - delete page from page cache
263 * @page: the page which the kernel is trying to remove from page cache
264 *
265 * This must be called only on pages that have been verified to be in the page
266 * cache and locked. It will never put the page into the free list, the caller
267 * has a reference on the page.
268 */
269void delete_from_page_cache(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700270{
Kirill A. Shutemov83929372016-07-26 15:26:04 -0700271 struct address_space *mapping = page_mapping(page);
Greg Thelenc4843a72015-05-22 17:13:16 -0400272 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273
Matt Mackallcd7619d2005-05-01 08:59:01 -0700274 BUG_ON(!PageLocked(page));
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700275 xa_lock_irqsave(&mapping->i_pages, flags);
Johannes Weiner62cccb82016-03-15 14:57:22 -0700276 __delete_from_page_cache(page, NULL);
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700277 xa_unlock_irqrestore(&mapping->i_pages, flags);
Linus Torvalds6072d132010-12-01 13:35:19 -0500278
Jan Kara59c66c52017-11-15 17:37:18 -0800279 page_cache_free_page(mapping, page);
Minchan Kim97cecb52011-03-22 16:30:53 -0700280}
281EXPORT_SYMBOL(delete_from_page_cache);
282
Jan Karaaa65c292017-11-15 17:37:33 -0800283/*
Matthew Wilcoxef8e5712017-12-04 03:59:45 -0500284 * page_cache_delete_batch - delete several pages from page cache
Jan Karaaa65c292017-11-15 17:37:33 -0800285 * @mapping: the mapping to which pages belong
286 * @pvec: pagevec with pages to delete
287 *
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700288 * The function walks over mapping->i_pages and removes pages passed in @pvec
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -0700289 * from the mapping. The function expects @pvec to be sorted by page index
290 * and is optimised for it to be dense.
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700291 * It tolerates holes in @pvec (mapping entries at those indices are not
Jan Karaaa65c292017-11-15 17:37:33 -0800292 * modified). The function expects only THP head pages to be present in the
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -0700293 * @pvec.
Jan Karaaa65c292017-11-15 17:37:33 -0800294 *
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700295 * The function expects the i_pages lock to be held.
Jan Karaaa65c292017-11-15 17:37:33 -0800296 */
Matthew Wilcoxef8e5712017-12-04 03:59:45 -0500297static void page_cache_delete_batch(struct address_space *mapping,
Jan Karaaa65c292017-11-15 17:37:33 -0800298 struct pagevec *pvec)
299{
Matthew Wilcoxef8e5712017-12-04 03:59:45 -0500300 XA_STATE(xas, &mapping->i_pages, pvec->pages[0]->index);
Jan Karaaa65c292017-11-15 17:37:33 -0800301 int total_pages = 0;
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -0700302 int i = 0;
Jan Karaaa65c292017-11-15 17:37:33 -0800303 struct page *page;
Jan Karaaa65c292017-11-15 17:37:33 -0800304
Matthew Wilcoxef8e5712017-12-04 03:59:45 -0500305 mapping_set_update(&xas, mapping);
306 xas_for_each(&xas, page, ULONG_MAX) {
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -0700307 if (i >= pagevec_count(pvec))
Jan Karaaa65c292017-11-15 17:37:33 -0800308 break;
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -0700309
310 /* A swap/dax/shadow entry got inserted? Skip it. */
Matthew Wilcox3159f942017-11-03 13:30:42 -0400311 if (xa_is_value(page))
Jan Karaaa65c292017-11-15 17:37:33 -0800312 continue;
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -0700313 /*
314 * A page got inserted in our range? Skip it. We have our
315 * pages locked so they are protected from being removed.
316 * If we see a page whose index is higher than ours, it
317 * means our page has been removed, which shouldn't be
318 * possible because we're holding the PageLock.
319 */
320 if (page != pvec->pages[i]) {
321 VM_BUG_ON_PAGE(page->index > pvec->pages[i]->index,
322 page);
323 continue;
Linus Torvalds69bf4b62019-07-05 19:55:18 -0700324 }
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -0700325
326 WARN_ON_ONCE(!PageLocked(page));
327
328 if (page->index == xas.xa_index)
329 page->mapping = NULL;
330 /* Leave page->index set: truncation lookup relies on it */
331
332 /*
333 * Move to the next page in the vector if this is a regular
334 * page or the index is of the last sub-page of this compound
335 * page.
336 */
337 if (page->index + compound_nr(page) - 1 == xas.xa_index)
338 i++;
Matthew Wilcoxef8e5712017-12-04 03:59:45 -0500339 xas_store(&xas, NULL);
Jan Karaaa65c292017-11-15 17:37:33 -0800340 total_pages++;
341 }
342 mapping->nrpages -= total_pages;
343}
344
345void delete_from_page_cache_batch(struct address_space *mapping,
346 struct pagevec *pvec)
347{
348 int i;
349 unsigned long flags;
350
351 if (!pagevec_count(pvec))
352 return;
353
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700354 xa_lock_irqsave(&mapping->i_pages, flags);
Jan Karaaa65c292017-11-15 17:37:33 -0800355 for (i = 0; i < pagevec_count(pvec); i++) {
356 trace_mm_filemap_delete_from_page_cache(pvec->pages[i]);
357
358 unaccount_page_cache_page(mapping, pvec->pages[i]);
359 }
Matthew Wilcoxef8e5712017-12-04 03:59:45 -0500360 page_cache_delete_batch(mapping, pvec);
Matthew Wilcoxb93b0162018-04-10 16:36:56 -0700361 xa_unlock_irqrestore(&mapping->i_pages, flags);
Jan Karaaa65c292017-11-15 17:37:33 -0800362
363 for (i = 0; i < pagevec_count(pvec); i++)
364 page_cache_free_page(mapping, pvec->pages[i]);
365}
366
Miklos Szeredid72d9e22016-07-29 14:10:57 +0200367int filemap_check_errors(struct address_space *mapping)
Dmitry Monakhov865ffef32013-04-29 15:08:42 -0700368{
369 int ret = 0;
370 /* Check for outstanding write errors */
Jens Axboe7fcbbaf2014-05-22 11:54:16 -0700371 if (test_bit(AS_ENOSPC, &mapping->flags) &&
372 test_and_clear_bit(AS_ENOSPC, &mapping->flags))
Dmitry Monakhov865ffef32013-04-29 15:08:42 -0700373 ret = -ENOSPC;
Jens Axboe7fcbbaf2014-05-22 11:54:16 -0700374 if (test_bit(AS_EIO, &mapping->flags) &&
375 test_and_clear_bit(AS_EIO, &mapping->flags))
Dmitry Monakhov865ffef32013-04-29 15:08:42 -0700376 ret = -EIO;
377 return ret;
378}
Miklos Szeredid72d9e22016-07-29 14:10:57 +0200379EXPORT_SYMBOL(filemap_check_errors);
Dmitry Monakhov865ffef32013-04-29 15:08:42 -0700380
Jeff Layton76341ca2017-07-06 07:02:22 -0400381static int filemap_check_and_keep_errors(struct address_space *mapping)
382{
383 /* Check for outstanding write errors */
384 if (test_bit(AS_EIO, &mapping->flags))
385 return -EIO;
386 if (test_bit(AS_ENOSPC, &mapping->flags))
387 return -ENOSPC;
388 return 0;
389}
390
Linus Torvalds1da177e2005-04-16 15:20:36 -0700391/**
Randy Dunlap485bb992006-06-23 02:03:49 -0700392 * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
Martin Waitz67be2dd2005-05-01 08:59:26 -0700393 * @mapping: address space structure to write
394 * @start: offset in bytes where the range starts
Andrew Morton469eb4d2006-03-24 03:17:45 -0800395 * @end: offset in bytes where the range ends (inclusive)
Martin Waitz67be2dd2005-05-01 08:59:26 -0700396 * @sync_mode: enable synchronous operation
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 *
Randy Dunlap485bb992006-06-23 02:03:49 -0700398 * Start writeback against all of a mapping's dirty pages that lie
399 * within the byte offsets <start, end> inclusive.
400 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700401 * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
Randy Dunlap485bb992006-06-23 02:03:49 -0700402 * opposed to a regular memory cleansing writeback. The difference between
Linus Torvalds1da177e2005-04-16 15:20:36 -0700403 * these two operations is that if a dirty page/buffer is encountered, it must
404 * be waited upon, and not just skipped over.
Mike Rapoporta862f682019-03-05 15:48:42 -0800405 *
406 * Return: %0 on success, negative error code otherwise.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700407 */
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800408int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
409 loff_t end, int sync_mode)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700410{
411 int ret;
412 struct writeback_control wbc = {
413 .sync_mode = sync_mode,
Nick Piggin05fe4782009-01-06 14:39:08 -0800414 .nr_to_write = LONG_MAX,
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700415 .range_start = start,
416 .range_end = end,
Linus Torvalds1da177e2005-04-16 15:20:36 -0700417 };
418
Christoph Hellwigf56753a2020-09-24 08:51:40 +0200419 if (!mapping_can_writeback(mapping) ||
Konstantin Khlebnikovc3aab9a02019-09-23 15:34:45 -0700420 !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700421 return 0;
422
Tejun Heob16b1de2015-06-02 08:39:48 -0600423 wbc_attach_fdatawrite_inode(&wbc, mapping->host);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700424 ret = do_writepages(mapping, &wbc);
Tejun Heob16b1de2015-06-02 08:39:48 -0600425 wbc_detach_inode(&wbc);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700426 return ret;
427}
428
429static inline int __filemap_fdatawrite(struct address_space *mapping,
430 int sync_mode)
431{
OGAWA Hirofumi111ebb62006-06-23 02:03:26 -0700432 return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700433}
434
435int filemap_fdatawrite(struct address_space *mapping)
436{
437 return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
438}
439EXPORT_SYMBOL(filemap_fdatawrite);
440
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400441int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
Andrew Mortonebcf28e2006-03-24 03:18:04 -0800442 loff_t end)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700443{
444 return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
445}
Jan Karaf4c0a0f2008-07-11 19:27:31 -0400446EXPORT_SYMBOL(filemap_fdatawrite_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700447
Randy Dunlap485bb992006-06-23 02:03:49 -0700448/**
449 * filemap_flush - mostly a non-blocking flush
450 * @mapping: target address_space
451 *
Linus Torvalds1da177e2005-04-16 15:20:36 -0700452 * This is a mostly non-blocking flush. Not suitable for data-integrity
453 * purposes - I/O may not be started against all dirty pages.
Mike Rapoporta862f682019-03-05 15:48:42 -0800454 *
455 * Return: %0 on success, negative error code otherwise.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700456 */
457int filemap_flush(struct address_space *mapping)
458{
459 return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
460}
461EXPORT_SYMBOL(filemap_flush);
462
Goldwyn Rodrigues7fc9e472017-06-20 07:05:41 -0500463/**
464 * filemap_range_has_page - check if a page exists in range.
465 * @mapping: address space within which to check
466 * @start_byte: offset in bytes where the range starts
467 * @end_byte: offset in bytes where the range ends (inclusive)
468 *
469 * Find at least one page in the range supplied, usually used to check if
470 * direct writing in this range will trigger a writeback.
Mike Rapoporta862f682019-03-05 15:48:42 -0800471 *
472 * Return: %true if at least one page exists in the specified range,
473 * %false otherwise.
Goldwyn Rodrigues7fc9e472017-06-20 07:05:41 -0500474 */
475bool filemap_range_has_page(struct address_space *mapping,
476 loff_t start_byte, loff_t end_byte)
477{
Jan Karaf7b68042017-09-06 16:21:40 -0700478 struct page *page;
Matthew Wilcox8fa8e532018-01-16 06:26:49 -0500479 XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT);
480 pgoff_t max = end_byte >> PAGE_SHIFT;
Goldwyn Rodrigues7fc9e472017-06-20 07:05:41 -0500481
482 if (end_byte < start_byte)
483 return false;
484
Matthew Wilcox8fa8e532018-01-16 06:26:49 -0500485 rcu_read_lock();
486 for (;;) {
487 page = xas_find(&xas, max);
488 if (xas_retry(&xas, page))
489 continue;
490 /* Shadow entries don't count */
491 if (xa_is_value(page))
492 continue;
493 /*
494 * We don't need to try to pin this page; we're about to
495 * release the RCU lock anyway. It is enough to know that
496 * there was a page here recently.
497 */
498 break;
499 }
500 rcu_read_unlock();
Goldwyn Rodrigues7fc9e472017-06-20 07:05:41 -0500501
Matthew Wilcox8fa8e532018-01-16 06:26:49 -0500502 return page != NULL;
Goldwyn Rodrigues7fc9e472017-06-20 07:05:41 -0500503}
504EXPORT_SYMBOL(filemap_range_has_page);
505
Jeff Layton5e8fcc12017-07-06 07:02:24 -0400506static void __filemap_fdatawait_range(struct address_space *mapping,
Junichi Nomuraaa750fd2015-11-05 18:47:23 -0800507 loff_t start_byte, loff_t end_byte)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700508{
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300509 pgoff_t index = start_byte >> PAGE_SHIFT;
510 pgoff_t end = end_byte >> PAGE_SHIFT;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700511 struct pagevec pvec;
512 int nr_pages;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700513
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200514 if (end_byte < start_byte)
Jeff Layton5e8fcc12017-07-06 07:02:24 -0400515 return;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516
Mel Gorman86679822017-11-15 17:37:52 -0800517 pagevec_init(&pvec);
Jan Kara312e9d22017-11-15 17:35:05 -0800518 while (index <= end) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700519 unsigned i;
520
Jan Kara312e9d22017-11-15 17:35:05 -0800521 nr_pages = pagevec_lookup_range_tag(&pvec, mapping, &index,
Jan Kara67fd7072017-11-15 17:35:19 -0800522 end, PAGECACHE_TAG_WRITEBACK);
Jan Kara312e9d22017-11-15 17:35:05 -0800523 if (!nr_pages)
524 break;
525
Linus Torvalds1da177e2005-04-16 15:20:36 -0700526 for (i = 0; i < nr_pages; i++) {
527 struct page *page = pvec.pages[i];
528
Linus Torvalds1da177e2005-04-16 15:20:36 -0700529 wait_on_page_writeback(page);
Jeff Layton5e8fcc12017-07-06 07:02:24 -0400530 ClearPageError(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700531 }
532 pagevec_release(&pvec);
533 cond_resched();
534 }
Junichi Nomuraaa750fd2015-11-05 18:47:23 -0800535}
536
537/**
538 * filemap_fdatawait_range - wait for writeback to complete
539 * @mapping: address space structure to wait for
540 * @start_byte: offset in bytes where the range starts
541 * @end_byte: offset in bytes where the range ends (inclusive)
542 *
543 * Walk the list of under-writeback pages of the given address space
544 * in the given range and wait for all of them. Check error status of
545 * the address space and return it.
546 *
547 * Since the error status of the address space is cleared by this function,
548 * callers are responsible for checking the return value and handling and/or
549 * reporting the error.
Mike Rapoporta862f682019-03-05 15:48:42 -0800550 *
551 * Return: error status of the address space.
Junichi Nomuraaa750fd2015-11-05 18:47:23 -0800552 */
553int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
554 loff_t end_byte)
555{
Jeff Layton5e8fcc12017-07-06 07:02:24 -0400556 __filemap_fdatawait_range(mapping, start_byte, end_byte);
557 return filemap_check_errors(mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700558}
Jan Karad3bccb6f2009-08-17 19:30:27 +0200559EXPORT_SYMBOL(filemap_fdatawait_range);
560
561/**
Ross Zwisleraa0bfcd2019-06-20 17:05:37 -0400562 * filemap_fdatawait_range_keep_errors - wait for writeback to complete
563 * @mapping: address space structure to wait for
564 * @start_byte: offset in bytes where the range starts
565 * @end_byte: offset in bytes where the range ends (inclusive)
566 *
567 * Walk the list of under-writeback pages of the given address space in the
568 * given range and wait for all of them. Unlike filemap_fdatawait_range(),
569 * this function does not clear error status of the address space.
570 *
571 * Use this function if callers don't handle errors themselves. Expected
572 * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2),
573 * fsfreeze(8)
574 */
575int filemap_fdatawait_range_keep_errors(struct address_space *mapping,
576 loff_t start_byte, loff_t end_byte)
577{
578 __filemap_fdatawait_range(mapping, start_byte, end_byte);
579 return filemap_check_and_keep_errors(mapping);
580}
581EXPORT_SYMBOL(filemap_fdatawait_range_keep_errors);
582
583/**
Jeff Laytona823e452017-07-28 07:24:43 -0400584 * file_fdatawait_range - wait for writeback to complete
585 * @file: file pointing to address space structure to wait for
586 * @start_byte: offset in bytes where the range starts
587 * @end_byte: offset in bytes where the range ends (inclusive)
588 *
589 * Walk the list of under-writeback pages of the address space that file
590 * refers to, in the given range and wait for all of them. Check error
591 * status of the address space vs. the file->f_wb_err cursor and return it.
592 *
593 * Since the error status of the file is advanced by this function,
594 * callers are responsible for checking the return value and handling and/or
595 * reporting the error.
Mike Rapoporta862f682019-03-05 15:48:42 -0800596 *
597 * Return: error status of the address space vs. the file->f_wb_err cursor.
Jeff Laytona823e452017-07-28 07:24:43 -0400598 */
599int file_fdatawait_range(struct file *file, loff_t start_byte, loff_t end_byte)
600{
601 struct address_space *mapping = file->f_mapping;
602
603 __filemap_fdatawait_range(mapping, start_byte, end_byte);
604 return file_check_and_advance_wb_err(file);
605}
606EXPORT_SYMBOL(file_fdatawait_range);
607
608/**
Junichi Nomuraaa750fd2015-11-05 18:47:23 -0800609 * filemap_fdatawait_keep_errors - wait for writeback without clearing errors
610 * @mapping: address space structure to wait for
611 *
612 * Walk the list of under-writeback pages of the given address space
613 * and wait for all of them. Unlike filemap_fdatawait(), this function
614 * does not clear error status of the address space.
615 *
616 * Use this function if callers don't handle errors themselves. Expected
617 * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2),
618 * fsfreeze(8)
Mike Rapoporta862f682019-03-05 15:48:42 -0800619 *
620 * Return: error status of the address space.
Junichi Nomuraaa750fd2015-11-05 18:47:23 -0800621 */
Jeff Layton76341ca2017-07-06 07:02:22 -0400622int filemap_fdatawait_keep_errors(struct address_space *mapping)
Junichi Nomuraaa750fd2015-11-05 18:47:23 -0800623{
Jeff Laytonffb959b2017-07-31 10:29:38 -0400624 __filemap_fdatawait_range(mapping, 0, LLONG_MAX);
Jeff Layton76341ca2017-07-06 07:02:22 -0400625 return filemap_check_and_keep_errors(mapping);
Junichi Nomuraaa750fd2015-11-05 18:47:23 -0800626}
Jeff Layton76341ca2017-07-06 07:02:22 -0400627EXPORT_SYMBOL(filemap_fdatawait_keep_errors);
Junichi Nomuraaa750fd2015-11-05 18:47:23 -0800628
Konstantin Khlebnikov875d91b2019-09-23 15:34:48 -0700629/* Returns true if writeback might be needed or already in progress. */
Jeff Layton9326c9b2017-07-26 10:21:11 -0400630static bool mapping_needs_writeback(struct address_space *mapping)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700631{
Konstantin Khlebnikov875d91b2019-09-23 15:34:48 -0700632 if (dax_mapping(mapping))
633 return mapping->nrexceptional;
634
635 return mapping->nrpages;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700636}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700637
Randy Dunlap485bb992006-06-23 02:03:49 -0700638/**
639 * filemap_write_and_wait_range - write out & wait on a file range
640 * @mapping: the address_space for the pages
641 * @lstart: offset in bytes where the range starts
642 * @lend: offset in bytes where the range ends (inclusive)
643 *
Andrew Morton469eb4d2006-03-24 03:17:45 -0800644 * Write out and wait upon file offsets lstart->lend, inclusive.
645 *
mchehab@s-opensource.com0e056eb2017-03-30 17:11:36 -0300646 * Note that @lend is inclusive (describes the last byte to be written) so
Andrew Morton469eb4d2006-03-24 03:17:45 -0800647 * that this function can be used to write to the very end-of-file (end = -1).
Mike Rapoporta862f682019-03-05 15:48:42 -0800648 *
649 * Return: error status of the address space.
Andrew Morton469eb4d2006-03-24 03:17:45 -0800650 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700651int filemap_write_and_wait_range(struct address_space *mapping,
652 loff_t lstart, loff_t lend)
653{
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800654 int err = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700655
Jeff Layton9326c9b2017-07-26 10:21:11 -0400656 if (mapping_needs_writeback(mapping)) {
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800657 err = __filemap_fdatawrite_range(mapping, lstart, lend,
658 WB_SYNC_ALL);
Ira Weinyddf8f372020-01-30 22:12:07 -0800659 /*
660 * Even if the above returned error, the pages may be
661 * written partially (e.g. -ENOSPC), so we wait for it.
662 * But the -EIO is special case, it may indicate the worst
663 * thing (e.g. bug) happened, so we avoid waiting for it.
664 */
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800665 if (err != -EIO) {
Christoph Hellwig94004ed2009-09-30 22:16:33 +0200666 int err2 = filemap_fdatawait_range(mapping,
667 lstart, lend);
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800668 if (!err)
669 err = err2;
Jeff Laytoncbeaf952017-07-06 07:02:23 -0400670 } else {
671 /* Clear any previously stored errors */
672 filemap_check_errors(mapping);
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800673 }
Dmitry Monakhov865ffef32013-04-29 15:08:42 -0700674 } else {
675 err = filemap_check_errors(mapping);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700676 }
OGAWA Hirofumi28fd1292006-01-08 01:02:14 -0800677 return err;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678}
Chris Masonf6995582009-04-15 13:22:37 -0400679EXPORT_SYMBOL(filemap_write_and_wait_range);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700680
Jeff Layton5660e132017-07-06 07:02:25 -0400681void __filemap_set_wb_err(struct address_space *mapping, int err)
682{
Jeff Layton3acdfd22017-07-24 06:22:15 -0400683 errseq_t eseq = errseq_set(&mapping->wb_err, err);
Jeff Layton5660e132017-07-06 07:02:25 -0400684
685 trace_filemap_set_wb_err(mapping, eseq);
686}
687EXPORT_SYMBOL(__filemap_set_wb_err);
688
689/**
690 * file_check_and_advance_wb_err - report wb error (if any) that was previously
691 * and advance wb_err to current one
692 * @file: struct file on which the error is being reported
693 *
694 * When userland calls fsync (or something like nfsd does the equivalent), we
695 * want to report any writeback errors that occurred since the last fsync (or
696 * since the file was opened if there haven't been any).
697 *
698 * Grab the wb_err from the mapping. If it matches what we have in the file,
699 * then just quickly return 0. The file is all caught up.
700 *
701 * If it doesn't match, then take the mapping value, set the "seen" flag in
702 * it and try to swap it into place. If it works, or another task beat us
703 * to it with the new value, then update the f_wb_err and return the error
704 * portion. The error at this point must be reported via proper channels
705 * (a'la fsync, or NFS COMMIT operation, etc.).
706 *
707 * While we handle mapping->wb_err with atomic operations, the f_wb_err
708 * value is protected by the f_lock since we must ensure that it reflects
709 * the latest value swapped in for this file descriptor.
Mike Rapoporta862f682019-03-05 15:48:42 -0800710 *
711 * Return: %0 on success, negative error code otherwise.
Jeff Layton5660e132017-07-06 07:02:25 -0400712 */
713int file_check_and_advance_wb_err(struct file *file)
714{
715 int err = 0;
716 errseq_t old = READ_ONCE(file->f_wb_err);
717 struct address_space *mapping = file->f_mapping;
718
719 /* Locklessly handle the common case where nothing has changed */
720 if (errseq_check(&mapping->wb_err, old)) {
721 /* Something changed, must use slow path */
722 spin_lock(&file->f_lock);
723 old = file->f_wb_err;
724 err = errseq_check_and_advance(&mapping->wb_err,
725 &file->f_wb_err);
726 trace_file_check_and_advance_wb_err(file, old);
727 spin_unlock(&file->f_lock);
728 }
Jeff Laytonf4e222c2017-10-03 16:15:25 -0700729
730 /*
731 * We're mostly using this function as a drop in replacement for
732 * filemap_check_errors. Clear AS_EIO/AS_ENOSPC to emulate the effect
733 * that the legacy code would have had on these flags.
734 */
735 clear_bit(AS_EIO, &mapping->flags);
736 clear_bit(AS_ENOSPC, &mapping->flags);
Jeff Layton5660e132017-07-06 07:02:25 -0400737 return err;
738}
739EXPORT_SYMBOL(file_check_and_advance_wb_err);
740
741/**
742 * file_write_and_wait_range - write out & wait on a file range
743 * @file: file pointing to address_space with pages
744 * @lstart: offset in bytes where the range starts
745 * @lend: offset in bytes where the range ends (inclusive)
746 *
747 * Write out and wait upon file offsets lstart->lend, inclusive.
748 *
749 * Note that @lend is inclusive (describes the last byte to be written) so
750 * that this function can be used to write to the very end-of-file (end = -1).
751 *
752 * After writing out and waiting on the data, we check and advance the
753 * f_wb_err cursor to the latest value, and return any errors detected there.
Mike Rapoporta862f682019-03-05 15:48:42 -0800754 *
755 * Return: %0 on success, negative error code otherwise.
Jeff Layton5660e132017-07-06 07:02:25 -0400756 */
757int file_write_and_wait_range(struct file *file, loff_t lstart, loff_t lend)
758{
759 int err = 0, err2;
760 struct address_space *mapping = file->f_mapping;
761
Jeff Layton9326c9b2017-07-26 10:21:11 -0400762 if (mapping_needs_writeback(mapping)) {
Jeff Layton5660e132017-07-06 07:02:25 -0400763 err = __filemap_fdatawrite_range(mapping, lstart, lend,
764 WB_SYNC_ALL);
765 /* See comment of filemap_write_and_wait() */
766 if (err != -EIO)
767 __filemap_fdatawait_range(mapping, lstart, lend);
768 }
769 err2 = file_check_and_advance_wb_err(file);
770 if (!err)
771 err = err2;
772 return err;
773}
774EXPORT_SYMBOL(file_write_and_wait_range);
775
Randy Dunlap485bb992006-06-23 02:03:49 -0700776/**
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700777 * replace_page_cache_page - replace a pagecache page with a new one
778 * @old: page to be replaced
779 * @new: page to replace with
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700780 *
781 * This function replaces a page in the pagecache with a new one. On
782 * success it acquires the pagecache reference for the new page and
783 * drops it for the old page. Both the old and new pages must be
784 * locked. This function does not add the new page to the LRU, the
785 * caller must do that.
786 *
Matthew Wilcox74d60952017-11-17 10:01:45 -0500787 * The remove + add is atomic. This function cannot fail.
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700788 */
Baolin Wang1f7ef652021-02-24 12:01:42 -0800789void replace_page_cache_page(struct page *old, struct page *new)
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700790{
Matthew Wilcox74d60952017-11-17 10:01:45 -0500791 struct address_space *mapping = old->mapping;
792 void (*freepage)(struct page *) = mapping->a_ops->freepage;
793 pgoff_t offset = old->index;
794 XA_STATE(xas, &mapping->i_pages, offset);
795 unsigned long flags;
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700796
Sasha Levin309381fea2014-01-23 15:52:54 -0800797 VM_BUG_ON_PAGE(!PageLocked(old), old);
798 VM_BUG_ON_PAGE(!PageLocked(new), new);
799 VM_BUG_ON_PAGE(new->mapping, new);
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700800
Matthew Wilcox74d60952017-11-17 10:01:45 -0500801 get_page(new);
802 new->mapping = mapping;
803 new->index = offset;
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700804
Johannes Weiner0d1c2072020-06-03 16:01:54 -0700805 mem_cgroup_migrate(old, new);
806
Matthew Wilcox74d60952017-11-17 10:01:45 -0500807 xas_lock_irqsave(&xas, flags);
808 xas_store(&xas, new);
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700809
Matthew Wilcox74d60952017-11-17 10:01:45 -0500810 old->mapping = NULL;
811 /* hugetlb pages do not participate in page cache accounting. */
812 if (!PageHuge(old))
Johannes Weiner0d1c2072020-06-03 16:01:54 -0700813 __dec_lruvec_page_state(old, NR_FILE_PAGES);
Matthew Wilcox74d60952017-11-17 10:01:45 -0500814 if (!PageHuge(new))
Johannes Weiner0d1c2072020-06-03 16:01:54 -0700815 __inc_lruvec_page_state(new, NR_FILE_PAGES);
Matthew Wilcox74d60952017-11-17 10:01:45 -0500816 if (PageSwapBacked(old))
Johannes Weiner0d1c2072020-06-03 16:01:54 -0700817 __dec_lruvec_page_state(old, NR_SHMEM);
Matthew Wilcox74d60952017-11-17 10:01:45 -0500818 if (PageSwapBacked(new))
Johannes Weiner0d1c2072020-06-03 16:01:54 -0700819 __inc_lruvec_page_state(new, NR_SHMEM);
Matthew Wilcox74d60952017-11-17 10:01:45 -0500820 xas_unlock_irqrestore(&xas, flags);
Matthew Wilcox74d60952017-11-17 10:01:45 -0500821 if (freepage)
822 freepage(old);
823 put_page(old);
Miklos Szeredief6a3c62011-03-22 16:30:52 -0700824}
825EXPORT_SYMBOL_GPL(replace_page_cache_page);
826
Andrew Morton16c0cc02020-12-11 13:36:27 -0800827noinline int __add_to_page_cache_locked(struct page *page,
Alexei Starovoitov76cd6172020-08-27 15:01:10 -0700828 struct address_space *mapping,
Linus Torvaldsc4cf4982020-10-16 11:31:55 -0700829 pgoff_t offset, gfp_t gfp,
Alexei Starovoitov76cd6172020-08-27 15:01:10 -0700830 void **shadowp)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700831{
Matthew Wilcox74d60952017-11-17 10:01:45 -0500832 XA_STATE(xas, &mapping->i_pages, offset);
Johannes Weiner00501b52014-08-08 14:19:20 -0700833 int huge = PageHuge(page);
Nick Piggine2867812008-07-25 19:45:30 -0700834 int error;
Waiman Longda742402021-02-04 18:32:45 -0800835 bool charged = false;
Nick Piggine2867812008-07-25 19:45:30 -0700836
Sasha Levin309381fea2014-01-23 15:52:54 -0800837 VM_BUG_ON_PAGE(!PageLocked(page), page);
838 VM_BUG_ON_PAGE(PageSwapBacked(page), page);
Matthew Wilcox74d60952017-11-17 10:01:45 -0500839 mapping_set_update(&xas, mapping);
Nick Piggine2867812008-07-25 19:45:30 -0700840
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300841 get_page(page);
Kirill A. Shutemov66a0c8e2013-09-12 15:13:59 -0700842 page->mapping = mapping;
843 page->index = offset;
844
Johannes Weiner3fea5a42020-06-03 16:01:41 -0700845 if (!huge) {
Matthew Wilcox (Oracle)198b62f2020-10-15 20:05:20 -0700846 error = mem_cgroup_charge(page, current->mm, gfp);
Johannes Weiner3fea5a42020-06-03 16:01:41 -0700847 if (error)
848 goto error;
Waiman Longda742402021-02-04 18:32:45 -0800849 charged = true;
Johannes Weiner3fea5a42020-06-03 16:01:41 -0700850 }
851
Matthew Wilcox (Oracle)198b62f2020-10-15 20:05:20 -0700852 gfp &= GFP_RECLAIM_MASK;
853
Matthew Wilcox74d60952017-11-17 10:01:45 -0500854 do {
Matthew Wilcox (Oracle)198b62f2020-10-15 20:05:20 -0700855 unsigned int order = xa_get_order(xas.xa, xas.xa_index);
856 void *entry, *old = NULL;
857
858 if (order > thp_order(page))
859 xas_split_alloc(&xas, xa_load(xas.xa, xas.xa_index),
860 order, gfp);
Matthew Wilcox74d60952017-11-17 10:01:45 -0500861 xas_lock_irq(&xas);
Matthew Wilcox (Oracle)198b62f2020-10-15 20:05:20 -0700862 xas_for_each_conflict(&xas, entry) {
863 old = entry;
864 if (!xa_is_value(entry)) {
865 xas_set_err(&xas, -EEXIST);
866 goto unlock;
867 }
868 }
869
870 if (old) {
871 if (shadowp)
872 *shadowp = old;
873 /* entry may have been split before we acquired lock */
874 order = xa_get_order(xas.xa, xas.xa_index);
875 if (order > thp_order(page)) {
876 xas_split(&xas, old, order);
877 xas_reset(&xas);
878 }
879 }
880
Matthew Wilcox74d60952017-11-17 10:01:45 -0500881 xas_store(&xas, page);
882 if (xas_error(&xas))
883 goto unlock;
Michal Hocko4165b9b42015-06-24 16:57:24 -0700884
Matthew Wilcox (Oracle)198b62f2020-10-15 20:05:20 -0700885 if (old)
Matthew Wilcox74d60952017-11-17 10:01:45 -0500886 mapping->nrexceptional--;
Matthew Wilcox74d60952017-11-17 10:01:45 -0500887 mapping->nrpages++;
888
889 /* hugetlb pages do not participate in page cache accounting */
890 if (!huge)
Johannes Weiner0d1c2072020-06-03 16:01:54 -0700891 __inc_lruvec_page_state(page, NR_FILE_PAGES);
Matthew Wilcox74d60952017-11-17 10:01:45 -0500892unlock:
893 xas_unlock_irq(&xas);
Matthew Wilcox (Oracle)198b62f2020-10-15 20:05:20 -0700894 } while (xas_nomem(&xas, gfp));
Matthew Wilcox74d60952017-11-17 10:01:45 -0500895
Johannes Weiner3fea5a42020-06-03 16:01:41 -0700896 if (xas_error(&xas)) {
897 error = xas_error(&xas);
Waiman Longda742402021-02-04 18:32:45 -0800898 if (charged)
899 mem_cgroup_uncharge(page);
Matthew Wilcox74d60952017-11-17 10:01:45 -0500900 goto error;
Johannes Weiner3fea5a42020-06-03 16:01:41 -0700901 }
Matthew Wilcox74d60952017-11-17 10:01:45 -0500902
Kirill A. Shutemov66a0c8e2013-09-12 15:13:59 -0700903 trace_mm_filemap_add_to_page_cache(page);
904 return 0;
Matthew Wilcox74d60952017-11-17 10:01:45 -0500905error:
Kirill A. Shutemov66a0c8e2013-09-12 15:13:59 -0700906 page->mapping = NULL;
907 /* Leave page->index set: truncation relies upon it */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +0300908 put_page(page);
Johannes Weiner3fea5a42020-06-03 16:01:41 -0700909 return error;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700910}
Josef Bacikcfcbfb12019-05-13 17:21:04 -0700911ALLOW_ERROR_INJECTION(__add_to_page_cache_locked, ERRNO);
Johannes Weinera5289102014-04-03 14:47:51 -0700912
913/**
914 * add_to_page_cache_locked - add a locked page to the pagecache
915 * @page: page to add
916 * @mapping: the page's address_space
917 * @offset: page index
918 * @gfp_mask: page allocation mode
919 *
920 * This function is used to add a page to the pagecache. It must be locked.
921 * This function does not add the page to the LRU. The caller must do that.
Mike Rapoporta862f682019-03-05 15:48:42 -0800922 *
923 * Return: %0 on success, negative error code otherwise.
Johannes Weinera5289102014-04-03 14:47:51 -0700924 */
925int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
926 pgoff_t offset, gfp_t gfp_mask)
927{
928 return __add_to_page_cache_locked(page, mapping, offset,
929 gfp_mask, NULL);
930}
Nick Piggine2867812008-07-25 19:45:30 -0700931EXPORT_SYMBOL(add_to_page_cache_locked);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700932
933int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
Al Viro6daa0e22005-10-21 03:18:50 -0400934 pgoff_t offset, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700935{
Johannes Weinera5289102014-04-03 14:47:51 -0700936 void *shadow = NULL;
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700937 int ret;
938
Kirill A. Shutemov48c935a2016-01-15 16:51:24 -0800939 __SetPageLocked(page);
Johannes Weinera5289102014-04-03 14:47:51 -0700940 ret = __add_to_page_cache_locked(page, mapping, offset,
941 gfp_mask, &shadow);
942 if (unlikely(ret))
Kirill A. Shutemov48c935a2016-01-15 16:51:24 -0800943 __ClearPageLocked(page);
Johannes Weinera5289102014-04-03 14:47:51 -0700944 else {
945 /*
946 * The page might have been evicted from cache only
947 * recently, in which case it should be activated like
948 * any other repeatedly accessed page.
Rik van Rielf0281a02016-05-20 16:56:25 -0700949 * The exception is pages getting rewritten; evicting other
950 * data from the working set, only to cache data that will
951 * get overwritten with something else, is a waste of memory.
Johannes Weinera5289102014-04-03 14:47:51 -0700952 */
Johannes Weiner1899ad12018-10-26 15:06:04 -0700953 WARN_ON_ONCE(PageActive(page));
954 if (!(gfp_mask & __GFP_WRITE) && shadow)
955 workingset_refault(page, shadow);
Johannes Weinera5289102014-04-03 14:47:51 -0700956 lru_cache_add(page);
957 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700958 return ret;
959}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +0300960EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700961
Paul Jackson44110fe2006-03-24 03:16:04 -0800962#ifdef CONFIG_NUMA
Nick Piggin2ae88142006-10-28 10:38:23 -0700963struct page *__page_cache_alloc(gfp_t gfp)
Paul Jackson44110fe2006-03-24 03:16:04 -0800964{
Miao Xiec0ff7452010-05-24 14:32:08 -0700965 int n;
966 struct page *page;
967
Paul Jackson44110fe2006-03-24 03:16:04 -0800968 if (cpuset_do_page_mem_spread()) {
Mel Gormancc9a6c82012-03-21 16:34:11 -0700969 unsigned int cpuset_mems_cookie;
970 do {
Mel Gormand26914d2014-04-03 14:47:24 -0700971 cpuset_mems_cookie = read_mems_allowed_begin();
Mel Gormancc9a6c82012-03-21 16:34:11 -0700972 n = cpuset_mem_spread_node();
Vlastimil Babka96db8002015-09-08 15:03:50 -0700973 page = __alloc_pages_node(n, gfp, 0);
Mel Gormand26914d2014-04-03 14:47:24 -0700974 } while (!page && read_mems_allowed_retry(cpuset_mems_cookie));
Mel Gormancc9a6c82012-03-21 16:34:11 -0700975
Miao Xiec0ff7452010-05-24 14:32:08 -0700976 return page;
Paul Jackson44110fe2006-03-24 03:16:04 -0800977 }
Nick Piggin2ae88142006-10-28 10:38:23 -0700978 return alloc_pages(gfp, 0);
Paul Jackson44110fe2006-03-24 03:16:04 -0800979}
Nick Piggin2ae88142006-10-28 10:38:23 -0700980EXPORT_SYMBOL(__page_cache_alloc);
Paul Jackson44110fe2006-03-24 03:16:04 -0800981#endif
982
Linus Torvalds1da177e2005-04-16 15:20:36 -0700983/*
984 * In order to wait for pages to become available there must be
985 * waitqueues associated with pages. By using a hash table of
986 * waitqueues where the bucket discipline is to maintain all
987 * waiters on the same queue and wake all when any of the pages
988 * become available, and for the woken contexts to check to be
989 * sure the appropriate page became available, this saves space
990 * at a cost of "thundering herd" phenomena during rare hash
991 * collisions.
992 */
Nicholas Piggin62906022016-12-25 13:00:30 +1000993#define PAGE_WAIT_TABLE_BITS 8
994#define PAGE_WAIT_TABLE_SIZE (1 << PAGE_WAIT_TABLE_BITS)
995static wait_queue_head_t page_wait_table[PAGE_WAIT_TABLE_SIZE] __cacheline_aligned;
996
997static wait_queue_head_t *page_waitqueue(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700998{
Nicholas Piggin62906022016-12-25 13:00:30 +1000999 return &page_wait_table[hash_ptr(page, PAGE_WAIT_TABLE_BITS)];
Linus Torvalds1da177e2005-04-16 15:20:36 -07001000}
Nicholas Piggin62906022016-12-25 13:00:30 +10001001
1002void __init pagecache_init(void)
1003{
1004 int i;
1005
1006 for (i = 0; i < PAGE_WAIT_TABLE_SIZE; i++)
1007 init_waitqueue_head(&page_wait_table[i]);
1008
1009 page_writeback_init();
1010}
1011
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001012/*
1013 * The page wait code treats the "wait->flags" somewhat unusually, because
Linus Torvalds5868ec22020-09-20 10:38:47 -07001014 * we have multiple different kinds of waits, not just the usual "exclusive"
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001015 * one.
1016 *
1017 * We have:
1018 *
1019 * (a) no special bits set:
1020 *
1021 * We're just waiting for the bit to be released, and when a waker
1022 * calls the wakeup function, we set WQ_FLAG_WOKEN and wake it up,
1023 * and remove it from the wait queue.
1024 *
1025 * Simple and straightforward.
1026 *
1027 * (b) WQ_FLAG_EXCLUSIVE:
1028 *
1029 * The waiter is waiting to get the lock, and only one waiter should
1030 * be woken up to avoid any thundering herd behavior. We'll set the
1031 * WQ_FLAG_WOKEN bit, wake it up, and remove it from the wait queue.
1032 *
1033 * This is the traditional exclusive wait.
1034 *
Linus Torvalds5868ec22020-09-20 10:38:47 -07001035 * (c) WQ_FLAG_EXCLUSIVE | WQ_FLAG_CUSTOM:
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001036 *
1037 * The waiter is waiting to get the bit, and additionally wants the
1038 * lock to be transferred to it for fair lock behavior. If the lock
1039 * cannot be taken, we stop walking the wait queue without waking
1040 * the waiter.
1041 *
1042 * This is the "fair lock handoff" case, and in addition to setting
1043 * WQ_FLAG_WOKEN, we set WQ_FLAG_DONE to let the waiter easily see
1044 * that it now has the lock.
1045 */
Ingo Molnarac6424b2017-06-20 12:06:13 +02001046static int wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *arg)
Nicholas Piggin62906022016-12-25 13:00:30 +10001047{
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001048 unsigned int flags;
Nicholas Piggin62906022016-12-25 13:00:30 +10001049 struct wait_page_key *key = arg;
1050 struct wait_page_queue *wait_page
1051 = container_of(wait, struct wait_page_queue, wait);
1052
Linus Torvaldscdc8fcb2020-08-03 13:01:22 -07001053 if (!wake_page_match(wait_page, key))
Nicholas Piggin62906022016-12-25 13:00:30 +10001054 return 0;
Linus Torvalds3510ca22017-08-27 13:55:12 -07001055
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001056 /*
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001057 * If it's a lock handoff wait, we get the bit for it, and
1058 * stop walking (and do not wake it up) if we can't.
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001059 */
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001060 flags = wait->flags;
1061 if (flags & WQ_FLAG_EXCLUSIVE) {
1062 if (test_bit(key->bit_nr, &key->page->flags))
Linus Torvalds2a9127f2020-07-23 10:16:49 -07001063 return -1;
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001064 if (flags & WQ_FLAG_CUSTOM) {
1065 if (test_and_set_bit(key->bit_nr, &key->page->flags))
1066 return -1;
1067 flags |= WQ_FLAG_DONE;
1068 }
Linus Torvalds2a9127f2020-07-23 10:16:49 -07001069 }
Nicholas Piggin62906022016-12-25 13:00:30 +10001070
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001071 /*
1072 * We are holding the wait-queue lock, but the waiter that
1073 * is waiting for this will be checking the flags without
1074 * any locking.
1075 *
1076 * So update the flags atomically, and wake up the waiter
1077 * afterwards to avoid any races. This store-release pairs
1078 * with the load-acquire in wait_on_page_bit_common().
1079 */
1080 smp_store_release(&wait->flags, flags | WQ_FLAG_WOKEN);
Linus Torvalds2a9127f2020-07-23 10:16:49 -07001081 wake_up_state(wait->private, mode);
1082
1083 /*
1084 * Ok, we have successfully done what we're waiting for,
1085 * and we can unconditionally remove the wait entry.
1086 *
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001087 * Note that this pairs with the "finish_wait()" in the
1088 * waiter, and has to be the absolute last thing we do.
1089 * After this list_del_init(&wait->entry) the wait entry
Linus Torvalds2a9127f2020-07-23 10:16:49 -07001090 * might be de-allocated and the process might even have
1091 * exited.
Linus Torvalds2a9127f2020-07-23 10:16:49 -07001092 */
Linus Torvaldsc6fe44d2020-07-23 12:33:41 -07001093 list_del_init_careful(&wait->entry);
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001094 return (flags & WQ_FLAG_EXCLUSIVE) != 0;
Nicholas Piggin62906022016-12-25 13:00:30 +10001095}
1096
Nicholas Piggin74d81bf2017-02-22 15:44:41 -08001097static void wake_up_page_bit(struct page *page, int bit_nr)
Nicholas Piggin62906022016-12-25 13:00:30 +10001098{
1099 wait_queue_head_t *q = page_waitqueue(page);
1100 struct wait_page_key key;
1101 unsigned long flags;
Tim Chen11a19c72017-08-25 09:13:55 -07001102 wait_queue_entry_t bookmark;
Nicholas Piggin62906022016-12-25 13:00:30 +10001103
1104 key.page = page;
1105 key.bit_nr = bit_nr;
1106 key.page_match = 0;
1107
Tim Chen11a19c72017-08-25 09:13:55 -07001108 bookmark.flags = 0;
1109 bookmark.private = NULL;
1110 bookmark.func = NULL;
1111 INIT_LIST_HEAD(&bookmark.entry);
1112
Nicholas Piggin62906022016-12-25 13:00:30 +10001113 spin_lock_irqsave(&q->lock, flags);
Tim Chen11a19c72017-08-25 09:13:55 -07001114 __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
1115
1116 while (bookmark.flags & WQ_FLAG_BOOKMARK) {
1117 /*
1118 * Take a breather from holding the lock,
1119 * allow pages that finish wake up asynchronously
1120 * to acquire the lock and remove themselves
1121 * from wait queue
1122 */
1123 spin_unlock_irqrestore(&q->lock, flags);
1124 cpu_relax();
1125 spin_lock_irqsave(&q->lock, flags);
1126 __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
1127 }
1128
Nicholas Piggin62906022016-12-25 13:00:30 +10001129 /*
1130 * It is possible for other pages to have collided on the waitqueue
1131 * hash, so in that case check for a page match. That prevents a long-
1132 * term waiter
1133 *
1134 * It is still possible to miss a case here, when we woke page waiters
1135 * and removed them from the waitqueue, but there are still other
1136 * page waiters.
1137 */
1138 if (!waitqueue_active(q) || !key.page_match) {
1139 ClearPageWaiters(page);
1140 /*
1141 * It's possible to miss clearing Waiters here, when we woke
1142 * our page waiters, but the hashed waitqueue has waiters for
1143 * other pages on it.
1144 *
1145 * That's okay, it's a rare case. The next waker will clear it.
1146 */
1147 }
1148 spin_unlock_irqrestore(&q->lock, flags);
1149}
Nicholas Piggin74d81bf2017-02-22 15:44:41 -08001150
1151static void wake_up_page(struct page *page, int bit)
1152{
1153 if (!PageWaiters(page))
1154 return;
1155 wake_up_page_bit(page, bit);
1156}
Nicholas Piggin62906022016-12-25 13:00:30 +10001157
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001158/*
1159 * A choice of three behaviors for wait_on_page_bit_common():
1160 */
1161enum behavior {
1162 EXCLUSIVE, /* Hold ref to page and take the bit when woken, like
1163 * __lock_page() waiting on then setting PG_locked.
1164 */
1165 SHARED, /* Hold ref to page and check the bit when woken, like
1166 * wait_on_page_writeback() waiting on PG_writeback.
1167 */
1168 DROP, /* Drop ref to page before wait, no check when woken,
1169 * like put_and_wait_on_page_locked() on PG_locked.
1170 */
1171};
1172
Linus Torvalds2a9127f2020-07-23 10:16:49 -07001173/*
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001174 * Attempt to check (or get) the page bit, and mark us done
1175 * if successful.
Linus Torvalds2a9127f2020-07-23 10:16:49 -07001176 */
1177static inline bool trylock_page_bit_common(struct page *page, int bit_nr,
1178 struct wait_queue_entry *wait)
1179{
1180 if (wait->flags & WQ_FLAG_EXCLUSIVE) {
1181 if (test_and_set_bit(bit_nr, &page->flags))
1182 return false;
1183 } else if (test_bit(bit_nr, &page->flags))
1184 return false;
1185
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001186 wait->flags |= WQ_FLAG_WOKEN | WQ_FLAG_DONE;
Linus Torvalds2a9127f2020-07-23 10:16:49 -07001187 return true;
1188}
1189
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001190/* How many times do we accept lock stealing from under a waiter? */
1191int sysctl_page_lock_unfairness = 5;
1192
Nicholas Piggin62906022016-12-25 13:00:30 +10001193static inline int wait_on_page_bit_common(wait_queue_head_t *q,
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001194 struct page *page, int bit_nr, int state, enum behavior behavior)
Nicholas Piggin62906022016-12-25 13:00:30 +10001195{
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001196 int unfairness = sysctl_page_lock_unfairness;
Nicholas Piggin62906022016-12-25 13:00:30 +10001197 struct wait_page_queue wait_page;
Ingo Molnarac6424b2017-06-20 12:06:13 +02001198 wait_queue_entry_t *wait = &wait_page.wait;
Johannes Weinerb1d29ba2018-10-26 15:06:08 -07001199 bool thrashing = false;
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001200 bool delayacct = false;
Johannes Weinereb414682018-10-26 15:06:27 -07001201 unsigned long pflags;
Nicholas Piggin62906022016-12-25 13:00:30 +10001202
Johannes Weinereb414682018-10-26 15:06:27 -07001203 if (bit_nr == PG_locked &&
Johannes Weinerb1d29ba2018-10-26 15:06:08 -07001204 !PageUptodate(page) && PageWorkingset(page)) {
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001205 if (!PageSwapBacked(page)) {
Johannes Weinereb414682018-10-26 15:06:27 -07001206 delayacct_thrashing_start();
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001207 delayacct = true;
1208 }
Johannes Weinereb414682018-10-26 15:06:27 -07001209 psi_memstall_enter(&pflags);
Johannes Weinerb1d29ba2018-10-26 15:06:08 -07001210 thrashing = true;
1211 }
1212
Nicholas Piggin62906022016-12-25 13:00:30 +10001213 init_wait(wait);
1214 wait->func = wake_page_function;
1215 wait_page.page = page;
1216 wait_page.bit_nr = bit_nr;
1217
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001218repeat:
1219 wait->flags = 0;
1220 if (behavior == EXCLUSIVE) {
1221 wait->flags = WQ_FLAG_EXCLUSIVE;
1222 if (--unfairness < 0)
1223 wait->flags |= WQ_FLAG_CUSTOM;
1224 }
1225
Linus Torvalds2a9127f2020-07-23 10:16:49 -07001226 /*
1227 * Do one last check whether we can get the
1228 * page bit synchronously.
1229 *
1230 * Do the SetPageWaiters() marking before that
1231 * to let any waker we _just_ missed know they
1232 * need to wake us up (otherwise they'll never
1233 * even go to the slow case that looks at the
1234 * page queue), and add ourselves to the wait
1235 * queue if we need to sleep.
1236 *
1237 * This part needs to be done under the queue
1238 * lock to avoid races.
1239 */
1240 spin_lock_irq(&q->lock);
1241 SetPageWaiters(page);
1242 if (!trylock_page_bit_common(page, bit_nr, wait))
1243 __add_wait_queue_entry_tail(q, wait);
1244 spin_unlock_irq(&q->lock);
1245
1246 /*
1247 * From now on, all the logic will be based on
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001248 * the WQ_FLAG_WOKEN and WQ_FLAG_DONE flag, to
1249 * see whether the page bit testing has already
1250 * been done by the wake function.
Linus Torvalds2a9127f2020-07-23 10:16:49 -07001251 *
1252 * We can drop our reference to the page.
1253 */
1254 if (behavior == DROP)
1255 put_page(page);
1256
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001257 /*
1258 * Note that until the "finish_wait()", or until
1259 * we see the WQ_FLAG_WOKEN flag, we need to
1260 * be very careful with the 'wait->flags', because
1261 * we may race with a waker that sets them.
1262 */
Nicholas Piggin62906022016-12-25 13:00:30 +10001263 for (;;) {
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001264 unsigned int flags;
1265
Nicholas Piggin62906022016-12-25 13:00:30 +10001266 set_current_state(state);
1267
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001268 /* Loop until we've been woken or interrupted */
1269 flags = smp_load_acquire(&wait->flags);
1270 if (!(flags & WQ_FLAG_WOKEN)) {
1271 if (signal_pending_state(state, current))
1272 break;
1273
1274 io_schedule();
1275 continue;
1276 }
1277
1278 /* If we were non-exclusive, we're done */
1279 if (behavior != EXCLUSIVE)
Linus Torvaldsa8b169a2017-08-27 16:25:09 -07001280 break;
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001281
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001282 /* If the waker got the lock for us, we're done */
1283 if (flags & WQ_FLAG_DONE)
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001284 break;
Linus Torvalds2a9127f2020-07-23 10:16:49 -07001285
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001286 /*
1287 * Otherwise, if we're getting the lock, we need to
1288 * try to get it ourselves.
1289 *
1290 * And if that fails, we'll have to retry this all.
1291 */
1292 if (unlikely(test_and_set_bit(bit_nr, &page->flags)))
1293 goto repeat;
1294
1295 wait->flags |= WQ_FLAG_DONE;
1296 break;
Nicholas Piggin62906022016-12-25 13:00:30 +10001297 }
1298
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001299 /*
1300 * If a signal happened, this 'finish_wait()' may remove the last
1301 * waiter from the wait-queues, but the PageWaiters bit will remain
1302 * set. That's ok. The next wakeup will take care of it, and trying
1303 * to do it here would be difficult and prone to races.
1304 */
Nicholas Piggin62906022016-12-25 13:00:30 +10001305 finish_wait(q, wait);
1306
Johannes Weinereb414682018-10-26 15:06:27 -07001307 if (thrashing) {
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001308 if (delayacct)
Johannes Weinereb414682018-10-26 15:06:27 -07001309 delayacct_thrashing_end();
1310 psi_memstall_leave(&pflags);
1311 }
Johannes Weinerb1d29ba2018-10-26 15:06:08 -07001312
Nicholas Piggin62906022016-12-25 13:00:30 +10001313 /*
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001314 * NOTE! The wait->flags weren't stable until we've done the
1315 * 'finish_wait()', and we could have exited the loop above due
1316 * to a signal, and had a wakeup event happen after the signal
1317 * test but before the 'finish_wait()'.
1318 *
1319 * So only after the finish_wait() can we reliably determine
1320 * if we got woken up or not, so we can now figure out the final
1321 * return value based on that state without races.
1322 *
1323 * Also note that WQ_FLAG_WOKEN is sufficient for a non-exclusive
1324 * waiter, but an exclusive one requires WQ_FLAG_DONE.
Nicholas Piggin62906022016-12-25 13:00:30 +10001325 */
Linus Torvalds5ef64cc2020-09-13 14:05:35 -07001326 if (behavior == EXCLUSIVE)
1327 return wait->flags & WQ_FLAG_DONE ? 0 : -EINTR;
Nicholas Piggin62906022016-12-25 13:00:30 +10001328
Linus Torvalds2a9127f2020-07-23 10:16:49 -07001329 return wait->flags & WQ_FLAG_WOKEN ? 0 : -EINTR;
Nicholas Piggin62906022016-12-25 13:00:30 +10001330}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001331
Harvey Harrison920c7a52008-02-04 22:29:26 -08001332void wait_on_page_bit(struct page *page, int bit_nr)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001333{
Nicholas Piggin62906022016-12-25 13:00:30 +10001334 wait_queue_head_t *q = page_waitqueue(page);
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001335 wait_on_page_bit_common(q, page, bit_nr, TASK_UNINTERRUPTIBLE, SHARED);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001336}
1337EXPORT_SYMBOL(wait_on_page_bit);
1338
KOSAKI Motohirof62e00c2011-05-24 17:11:29 -07001339int wait_on_page_bit_killable(struct page *page, int bit_nr)
1340{
Nicholas Piggin62906022016-12-25 13:00:30 +10001341 wait_queue_head_t *q = page_waitqueue(page);
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001342 return wait_on_page_bit_common(q, page, bit_nr, TASK_KILLABLE, SHARED);
KOSAKI Motohirof62e00c2011-05-24 17:11:29 -07001343}
David Howells4343d002017-11-02 15:27:52 +00001344EXPORT_SYMBOL(wait_on_page_bit_killable);
KOSAKI Motohirof62e00c2011-05-24 17:11:29 -07001345
Linus Torvalds1da177e2005-04-16 15:20:36 -07001346/**
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001347 * put_and_wait_on_page_locked - Drop a reference and wait for it to be unlocked
1348 * @page: The page to wait for.
Matthew Wilcox (Oracle)48054622021-02-24 12:02:02 -08001349 * @state: The sleep state (TASK_KILLABLE, TASK_UNINTERRUPTIBLE, etc).
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001350 *
1351 * The caller should hold a reference on @page. They expect the page to
1352 * become unlocked relatively soon, but do not wish to hold up migration
1353 * (for example) by holding the reference while waiting for the page to
1354 * come unlocked. After this function returns, the caller should not
1355 * dereference @page.
Matthew Wilcox (Oracle)48054622021-02-24 12:02:02 -08001356 *
1357 * Return: 0 if the page was unlocked or -EINTR if interrupted by a signal.
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001358 */
Matthew Wilcox (Oracle)48054622021-02-24 12:02:02 -08001359int put_and_wait_on_page_locked(struct page *page, int state)
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001360{
1361 wait_queue_head_t *q;
1362
1363 page = compound_head(page);
1364 q = page_waitqueue(page);
Matthew Wilcox (Oracle)48054622021-02-24 12:02:02 -08001365 return wait_on_page_bit_common(q, page, PG_locked, state, DROP);
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001366}
1367
1368/**
David Howells385e1ca5f2009-04-03 16:42:39 +01001369 * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
Randy Dunlap697f6192009-04-13 14:39:54 -07001370 * @page: Page defining the wait queue of interest
1371 * @waiter: Waiter to add to the queue
David Howells385e1ca5f2009-04-03 16:42:39 +01001372 *
1373 * Add an arbitrary @waiter to the wait queue for the nominated @page.
1374 */
Ingo Molnarac6424b2017-06-20 12:06:13 +02001375void add_page_wait_queue(struct page *page, wait_queue_entry_t *waiter)
David Howells385e1ca5f2009-04-03 16:42:39 +01001376{
1377 wait_queue_head_t *q = page_waitqueue(page);
1378 unsigned long flags;
1379
1380 spin_lock_irqsave(&q->lock, flags);
Linus Torvalds9c3a8152017-08-28 16:45:40 -07001381 __add_wait_queue_entry_tail(q, waiter);
Nicholas Piggin62906022016-12-25 13:00:30 +10001382 SetPageWaiters(page);
David Howells385e1ca5f2009-04-03 16:42:39 +01001383 spin_unlock_irqrestore(&q->lock, flags);
1384}
1385EXPORT_SYMBOL_GPL(add_page_wait_queue);
1386
Linus Torvaldsb91e1302016-12-27 11:40:38 -08001387#ifndef clear_bit_unlock_is_negative_byte
1388
1389/*
1390 * PG_waiters is the high bit in the same byte as PG_lock.
1391 *
1392 * On x86 (and on many other architectures), we can clear PG_lock and
1393 * test the sign bit at the same time. But if the architecture does
1394 * not support that special operation, we just do this all by hand
1395 * instead.
1396 *
1397 * The read of PG_waiters has to be after (or concurrently with) PG_locked
Ethon Paulffceeb62020-06-04 16:49:22 -07001398 * being cleared, but a memory barrier should be unnecessary since it is
Linus Torvaldsb91e1302016-12-27 11:40:38 -08001399 * in the same byte as PG_locked.
1400 */
1401static inline bool clear_bit_unlock_is_negative_byte(long nr, volatile void *mem)
1402{
1403 clear_bit_unlock(nr, mem);
1404 /* smp_mb__after_atomic(); */
Olof Johansson98473f92016-12-29 14:16:07 -08001405 return test_bit(PG_waiters, mem);
Linus Torvaldsb91e1302016-12-27 11:40:38 -08001406}
1407
1408#endif
1409
David Howells385e1ca5f2009-04-03 16:42:39 +01001410/**
Randy Dunlap485bb992006-06-23 02:03:49 -07001411 * unlock_page - unlock a locked page
Linus Torvalds1da177e2005-04-16 15:20:36 -07001412 * @page: the page
1413 *
Miaohe Lin0e9aa672020-10-15 20:09:58 -07001414 * Unlocks the page and wakes up sleepers in wait_on_page_locked().
Linus Torvalds1da177e2005-04-16 15:20:36 -07001415 * Also wakes sleepers in wait_on_page_writeback() because the wakeup
Masanari Iidada3dae52014-09-09 01:27:23 +09001416 * mechanism between PageLocked pages and PageWriteback pages is shared.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001417 * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
1418 *
Linus Torvaldsb91e1302016-12-27 11:40:38 -08001419 * Note that this depends on PG_waiters being the sign bit in the byte
1420 * that contains PG_locked - thus the BUILD_BUG_ON(). That allows us to
1421 * clear the PG_locked bit and test PG_waiters at the same time fairly
1422 * portably (architectures that do LL/SC can test any bit, while x86 can
1423 * test the sign bit).
Linus Torvalds1da177e2005-04-16 15:20:36 -07001424 */
Harvey Harrison920c7a52008-02-04 22:29:26 -08001425void unlock_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001426{
Linus Torvaldsb91e1302016-12-27 11:40:38 -08001427 BUILD_BUG_ON(PG_waiters != 7);
Kirill A. Shutemov48c935a2016-01-15 16:51:24 -08001428 page = compound_head(page);
Sasha Levin309381fea2014-01-23 15:52:54 -08001429 VM_BUG_ON_PAGE(!PageLocked(page), page);
Linus Torvaldsb91e1302016-12-27 11:40:38 -08001430 if (clear_bit_unlock_is_negative_byte(PG_locked, &page->flags))
1431 wake_up_page_bit(page, PG_locked);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001432}
1433EXPORT_SYMBOL(unlock_page);
1434
Randy Dunlap485bb992006-06-23 02:03:49 -07001435/**
1436 * end_page_writeback - end writeback against a page
1437 * @page: the page
Linus Torvalds1da177e2005-04-16 15:20:36 -07001438 */
1439void end_page_writeback(struct page *page)
1440{
Mel Gorman888cf2d2014-06-04 16:10:34 -07001441 /*
1442 * TestClearPageReclaim could be used here but it is an atomic
1443 * operation and overkill in this particular case. Failing to
1444 * shuffle a page marked for immediate reclaim is too mild to
1445 * justify taking an atomic operation penalty at the end of
1446 * ever page writeback.
1447 */
1448 if (PageReclaim(page)) {
1449 ClearPageReclaim(page);
Miklos Szerediac6aadb2008-04-28 02:12:38 -07001450 rotate_reclaimable_page(page);
Mel Gorman888cf2d2014-06-04 16:10:34 -07001451 }
Miklos Szerediac6aadb2008-04-28 02:12:38 -07001452
Hugh Dickins073861e2020-11-24 08:46:43 -08001453 /*
1454 * Writeback does not hold a page reference of its own, relying
1455 * on truncation to wait for the clearing of PG_writeback.
1456 * But here we must make sure that the page is not freed and
1457 * reused before the wake_up_page().
1458 */
1459 get_page(page);
Miklos Szerediac6aadb2008-04-28 02:12:38 -07001460 if (!test_clear_page_writeback(page))
1461 BUG();
1462
Peter Zijlstra4e857c52014-03-17 18:06:10 +01001463 smp_mb__after_atomic();
Linus Torvalds1da177e2005-04-16 15:20:36 -07001464 wake_up_page(page, PG_writeback);
Hugh Dickins073861e2020-11-24 08:46:43 -08001465 put_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001466}
1467EXPORT_SYMBOL(end_page_writeback);
1468
Matthew Wilcox57d99842014-06-04 16:07:45 -07001469/*
1470 * After completing I/O on a page, call this routine to update the page
1471 * flags appropriately
1472 */
Jens Axboec11f0c02016-08-05 08:11:04 -06001473void page_endio(struct page *page, bool is_write, int err)
Matthew Wilcox57d99842014-06-04 16:07:45 -07001474{
Jens Axboec11f0c02016-08-05 08:11:04 -06001475 if (!is_write) {
Matthew Wilcox57d99842014-06-04 16:07:45 -07001476 if (!err) {
1477 SetPageUptodate(page);
1478 } else {
1479 ClearPageUptodate(page);
1480 SetPageError(page);
1481 }
1482 unlock_page(page);
Mike Christieabf54542016-08-04 14:23:34 -06001483 } else {
Matthew Wilcox57d99842014-06-04 16:07:45 -07001484 if (err) {
Minchan Kimdd8416c2017-02-24 14:59:59 -08001485 struct address_space *mapping;
1486
Matthew Wilcox57d99842014-06-04 16:07:45 -07001487 SetPageError(page);
Minchan Kimdd8416c2017-02-24 14:59:59 -08001488 mapping = page_mapping(page);
1489 if (mapping)
1490 mapping_set_error(mapping, err);
Matthew Wilcox57d99842014-06-04 16:07:45 -07001491 }
1492 end_page_writeback(page);
1493 }
1494}
1495EXPORT_SYMBOL_GPL(page_endio);
1496
Randy Dunlap485bb992006-06-23 02:03:49 -07001497/**
1498 * __lock_page - get a lock on the page, assuming we need to sleep to get it
Randy Dunlap87066752017-02-22 15:44:44 -08001499 * @__page: the page to lock
Linus Torvalds1da177e2005-04-16 15:20:36 -07001500 */
Nicholas Piggin62906022016-12-25 13:00:30 +10001501void __lock_page(struct page *__page)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001502{
Nicholas Piggin62906022016-12-25 13:00:30 +10001503 struct page *page = compound_head(__page);
1504 wait_queue_head_t *q = page_waitqueue(page);
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001505 wait_on_page_bit_common(q, page, PG_locked, TASK_UNINTERRUPTIBLE,
1506 EXCLUSIVE);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001507}
1508EXPORT_SYMBOL(__lock_page);
1509
Nicholas Piggin62906022016-12-25 13:00:30 +10001510int __lock_page_killable(struct page *__page)
Matthew Wilcox2687a352007-12-06 11:18:49 -05001511{
Nicholas Piggin62906022016-12-25 13:00:30 +10001512 struct page *page = compound_head(__page);
1513 wait_queue_head_t *q = page_waitqueue(page);
Hugh Dickins9a1ea432018-12-28 00:36:14 -08001514 return wait_on_page_bit_common(q, page, PG_locked, TASK_KILLABLE,
1515 EXCLUSIVE);
Matthew Wilcox2687a352007-12-06 11:18:49 -05001516}
Evgeniy Polyakov18bc0bb2009-02-09 17:02:42 +03001517EXPORT_SYMBOL_GPL(__lock_page_killable);
Matthew Wilcox2687a352007-12-06 11:18:49 -05001518
Jens Axboedd3e6d52020-05-22 09:12:09 -06001519int __lock_page_async(struct page *page, struct wait_page_queue *wait)
1520{
Matthew Wilcox (Oracle)f32b5dd2021-02-24 12:02:09 -08001521 struct wait_queue_head *q = page_waitqueue(page);
1522 int ret = 0;
1523
1524 wait->page = page;
1525 wait->bit_nr = PG_locked;
1526
1527 spin_lock_irq(&q->lock);
1528 __add_wait_queue_entry_tail(q, &wait->wait);
1529 SetPageWaiters(page);
1530 ret = !trylock_page(page);
1531 /*
1532 * If we were successful now, we know we're still on the
1533 * waitqueue as we're still under the lock. This means it's
1534 * safe to remove and return success, we know the callback
1535 * isn't going to trigger.
1536 */
1537 if (!ret)
1538 __remove_wait_queue(q, &wait->wait);
1539 else
1540 ret = -EIOCBQUEUED;
1541 spin_unlock_irq(&q->lock);
1542 return ret;
Jens Axboedd3e6d52020-05-22 09:12:09 -06001543}
1544
Paul Cassella9a95f3c2014-08-06 16:07:24 -07001545/*
1546 * Return values:
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07001547 * 1 - page is locked; mmap_lock is still held.
Paul Cassella9a95f3c2014-08-06 16:07:24 -07001548 * 0 - page is not locked.
Michel Lespinasse3e4e28c2020-06-08 21:33:51 -07001549 * mmap_lock has been released (mmap_read_unlock(), unless flags had both
Paul Cassella9a95f3c2014-08-06 16:07:24 -07001550 * FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07001551 * which case mmap_lock is still held.
Paul Cassella9a95f3c2014-08-06 16:07:24 -07001552 *
1553 * If neither ALLOW_RETRY nor KILLABLE are set, will always return 1
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07001554 * with the page locked and the mmap_lock unperturbed.
Paul Cassella9a95f3c2014-08-06 16:07:24 -07001555 */
Michel Lespinassed065bd82010-10-26 14:21:57 -07001556int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
1557 unsigned int flags)
1558{
Peter Xu4064b982020-04-01 21:08:45 -07001559 if (fault_flag_allow_retry_first(flags)) {
KOSAKI Motohiro37b23e02011-05-24 17:11:30 -07001560 /*
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07001561 * CAUTION! In this case, mmap_lock is not released
KOSAKI Motohiro37b23e02011-05-24 17:11:30 -07001562 * even though return 0.
1563 */
1564 if (flags & FAULT_FLAG_RETRY_NOWAIT)
1565 return 0;
1566
Michel Lespinassed8ed45c2020-06-08 21:33:25 -07001567 mmap_read_unlock(mm);
KOSAKI Motohiro37b23e02011-05-24 17:11:30 -07001568 if (flags & FAULT_FLAG_KILLABLE)
1569 wait_on_page_locked_killable(page);
1570 else
Gleb Natapov318b2752011-03-22 16:30:51 -07001571 wait_on_page_locked(page);
Michel Lespinassed065bd82010-10-26 14:21:57 -07001572 return 0;
1573 }
Hailong Liu800bca72020-12-14 19:05:02 -08001574 if (flags & FAULT_FLAG_KILLABLE) {
1575 int ret;
1576
1577 ret = __lock_page_killable(page);
1578 if (ret) {
1579 mmap_read_unlock(mm);
1580 return 0;
1581 }
1582 } else {
1583 __lock_page(page);
1584 }
1585 return 1;
1586
Michel Lespinassed065bd82010-10-26 14:21:57 -07001587}
1588
Randy Dunlap485bb992006-06-23 02:03:49 -07001589/**
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001590 * page_cache_next_miss() - Find the next gap in the page cache.
1591 * @mapping: Mapping.
1592 * @index: Index.
1593 * @max_scan: Maximum range to search.
Johannes Weinere7b563b2014-04-03 14:47:44 -07001594 *
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001595 * Search the range [index, min(index + max_scan - 1, ULONG_MAX)] for the
1596 * gap with the lowest index.
Johannes Weinere7b563b2014-04-03 14:47:44 -07001597 *
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001598 * This function may be called under the rcu_read_lock. However, this will
1599 * not atomically search a snapshot of the cache at a single point in time.
1600 * For example, if a gap is created at index 5, then subsequently a gap is
1601 * created at index 10, page_cache_next_miss covering both indices may
1602 * return 10 if called under the rcu_read_lock.
Johannes Weinere7b563b2014-04-03 14:47:44 -07001603 *
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001604 * Return: The index of the gap if found, otherwise an index outside the
1605 * range specified (in which case 'return - index >= max_scan' will be true).
1606 * In the rare case of index wrap-around, 0 will be returned.
Johannes Weinere7b563b2014-04-03 14:47:44 -07001607 */
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001608pgoff_t page_cache_next_miss(struct address_space *mapping,
Johannes Weinere7b563b2014-04-03 14:47:44 -07001609 pgoff_t index, unsigned long max_scan)
1610{
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001611 XA_STATE(xas, &mapping->i_pages, index);
Johannes Weinere7b563b2014-04-03 14:47:44 -07001612
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001613 while (max_scan--) {
1614 void *entry = xas_next(&xas);
1615 if (!entry || xa_is_value(entry))
Johannes Weinere7b563b2014-04-03 14:47:44 -07001616 break;
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001617 if (xas.xa_index == 0)
Johannes Weinere7b563b2014-04-03 14:47:44 -07001618 break;
1619 }
1620
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001621 return xas.xa_index;
Johannes Weinere7b563b2014-04-03 14:47:44 -07001622}
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001623EXPORT_SYMBOL(page_cache_next_miss);
Johannes Weinere7b563b2014-04-03 14:47:44 -07001624
1625/**
Laurent Dufour2346a562019-05-13 17:21:29 -07001626 * page_cache_prev_miss() - Find the previous gap in the page cache.
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001627 * @mapping: Mapping.
1628 * @index: Index.
1629 * @max_scan: Maximum range to search.
Johannes Weinere7b563b2014-04-03 14:47:44 -07001630 *
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001631 * Search the range [max(index - max_scan + 1, 0), index] for the
1632 * gap with the highest index.
Johannes Weinere7b563b2014-04-03 14:47:44 -07001633 *
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001634 * This function may be called under the rcu_read_lock. However, this will
1635 * not atomically search a snapshot of the cache at a single point in time.
1636 * For example, if a gap is created at index 10, then subsequently a gap is
1637 * created at index 5, page_cache_prev_miss() covering both indices may
1638 * return 5 if called under the rcu_read_lock.
Johannes Weinere7b563b2014-04-03 14:47:44 -07001639 *
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001640 * Return: The index of the gap if found, otherwise an index outside the
1641 * range specified (in which case 'index - return >= max_scan' will be true).
1642 * In the rare case of wrap-around, ULONG_MAX will be returned.
Johannes Weinere7b563b2014-04-03 14:47:44 -07001643 */
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001644pgoff_t page_cache_prev_miss(struct address_space *mapping,
Johannes Weinere7b563b2014-04-03 14:47:44 -07001645 pgoff_t index, unsigned long max_scan)
1646{
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001647 XA_STATE(xas, &mapping->i_pages, index);
Johannes Weinere7b563b2014-04-03 14:47:44 -07001648
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001649 while (max_scan--) {
1650 void *entry = xas_prev(&xas);
1651 if (!entry || xa_is_value(entry))
Johannes Weinere7b563b2014-04-03 14:47:44 -07001652 break;
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001653 if (xas.xa_index == ULONG_MAX)
Johannes Weinere7b563b2014-04-03 14:47:44 -07001654 break;
1655 }
1656
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001657 return xas.xa_index;
Johannes Weinere7b563b2014-04-03 14:47:44 -07001658}
Matthew Wilcox0d3f9292017-11-21 14:07:06 -05001659EXPORT_SYMBOL(page_cache_prev_miss);
Johannes Weinere7b563b2014-04-03 14:47:44 -07001660
1661/**
Johannes Weiner0cd61442014-04-03 14:47:46 -07001662 * find_get_entry - find and get a page cache entry
Randy Dunlap485bb992006-06-23 02:03:49 -07001663 * @mapping: the address_space to search
Matthew Wilcox (Oracle)a6de4b42020-10-13 16:51:34 -07001664 * @index: The page cache index.
Randy Dunlap485bb992006-06-23 02:03:49 -07001665 *
Johannes Weiner0cd61442014-04-03 14:47:46 -07001666 * Looks up the page cache slot at @mapping & @offset. If there is a
Matthew Wilcox (Oracle)a6de4b42020-10-13 16:51:34 -07001667 * page cache page, the head page is returned with an increased refcount.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001668 *
Johannes Weiner139b6a62014-05-06 12:50:05 -07001669 * If the slot holds a shadow entry of a previously evicted page, or a
1670 * swap entry from shmem/tmpfs, it is returned.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001671 *
Matthew Wilcox (Oracle)a6de4b42020-10-13 16:51:34 -07001672 * Return: The head page or shadow entry, %NULL if nothing is found.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001673 */
Matthew Wilcox (Oracle)a6de4b42020-10-13 16:51:34 -07001674struct page *find_get_entry(struct address_space *mapping, pgoff_t index)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001675{
Matthew Wilcox (Oracle)a6de4b42020-10-13 16:51:34 -07001676 XA_STATE(xas, &mapping->i_pages, index);
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07001677 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001678
Nick Piggina60637c2008-07-25 19:45:31 -07001679 rcu_read_lock();
1680repeat:
Matthew Wilcox4c7472c2018-05-16 16:12:50 -04001681 xas_reset(&xas);
1682 page = xas_load(&xas);
1683 if (xas_retry(&xas, page))
1684 goto repeat;
1685 /*
1686 * A shadow entry of a recently evicted page, or a swap entry from
1687 * shmem/tmpfs. Return it without attempting to raise page count.
1688 */
1689 if (!page || xa_is_value(page))
1690 goto out;
Kirill A. Shutemov83929372016-07-26 15:26:04 -07001691
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07001692 if (!page_cache_get_speculative(page))
Matthew Wilcox4c7472c2018-05-16 16:12:50 -04001693 goto repeat;
Nick Piggina60637c2008-07-25 19:45:31 -07001694
Matthew Wilcox4c7472c2018-05-16 16:12:50 -04001695 /*
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07001696 * Has the page moved or been split?
Matthew Wilcox4c7472c2018-05-16 16:12:50 -04001697 * This is part of the lockless pagecache protocol. See
1698 * include/linux/pagemap.h for details.
1699 */
1700 if (unlikely(page != xas_reload(&xas))) {
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07001701 put_page(page);
Matthew Wilcox4c7472c2018-05-16 16:12:50 -04001702 goto repeat;
Nick Piggina60637c2008-07-25 19:45:31 -07001703 }
Nick Piggin27d20fd2010-11-11 14:05:19 -08001704out:
Nick Piggina60637c2008-07-25 19:45:31 -07001705 rcu_read_unlock();
1706
Linus Torvalds1da177e2005-04-16 15:20:36 -07001707 return page;
1708}
Linus Torvalds1da177e2005-04-16 15:20:36 -07001709
Randy Dunlap485bb992006-06-23 02:03:49 -07001710/**
Matthew Wilcox (Oracle)63ec1972020-10-13 16:51:38 -07001711 * find_lock_entry - Locate and lock a page cache entry.
1712 * @mapping: The address_space to search.
1713 * @index: The page cache index.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001714 *
Matthew Wilcox (Oracle)63ec1972020-10-13 16:51:38 -07001715 * Looks up the page at @mapping & @index. If there is a page in the
1716 * cache, the head page is returned locked and with an increased refcount.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001717 *
Johannes Weiner139b6a62014-05-06 12:50:05 -07001718 * If the slot holds a shadow entry of a previously evicted page, or a
1719 * swap entry from shmem/tmpfs, it is returned.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001720 *
Matthew Wilcox (Oracle)63ec1972020-10-13 16:51:38 -07001721 * Context: May sleep.
1722 * Return: The head page or shadow entry, %NULL if nothing is found.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001723 */
Matthew Wilcox (Oracle)63ec1972020-10-13 16:51:38 -07001724struct page *find_lock_entry(struct address_space *mapping, pgoff_t index)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001725{
1726 struct page *page;
1727
Linus Torvalds1da177e2005-04-16 15:20:36 -07001728repeat:
Matthew Wilcox (Oracle)63ec1972020-10-13 16:51:38 -07001729 page = find_get_entry(mapping, index);
Matthew Wilcox4c7472c2018-05-16 16:12:50 -04001730 if (page && !xa_is_value(page)) {
Nick Piggina60637c2008-07-25 19:45:31 -07001731 lock_page(page);
1732 /* Has the page been truncated? */
Matthew Wilcox (Oracle)63ec1972020-10-13 16:51:38 -07001733 if (unlikely(page->mapping != mapping)) {
Nick Piggina60637c2008-07-25 19:45:31 -07001734 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03001735 put_page(page);
Nick Piggina60637c2008-07-25 19:45:31 -07001736 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001737 }
Matthew Wilcox (Oracle)63ec1972020-10-13 16:51:38 -07001738 VM_BUG_ON_PAGE(!thp_contains(page, index), page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001739 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07001740 return page;
1741}
Johannes Weiner0cd61442014-04-03 14:47:46 -07001742
1743/**
Matthew Wilcox (Oracle)2294b322020-04-01 21:05:07 -07001744 * pagecache_get_page - Find and get a reference to a page.
1745 * @mapping: The address_space to search.
1746 * @index: The page index.
1747 * @fgp_flags: %FGP flags modify how the page is returned.
1748 * @gfp_mask: Memory allocation flags to use if %FGP_CREAT is specified.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001749 *
Matthew Wilcox (Oracle)2294b322020-04-01 21:05:07 -07001750 * Looks up the page cache entry at @mapping & @index.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001751 *
Matthew Wilcox (Oracle)2294b322020-04-01 21:05:07 -07001752 * @fgp_flags can be zero or more of these flags:
Johannes Weiner0cd61442014-04-03 14:47:46 -07001753 *
Matthew Wilcox (Oracle)2294b322020-04-01 21:05:07 -07001754 * * %FGP_ACCESSED - The page will be marked accessed.
1755 * * %FGP_LOCK - The page is returned locked.
Matthew Wilcox (Oracle)a8cf7f22020-10-13 16:51:41 -07001756 * * %FGP_HEAD - If the page is present and a THP, return the head page
1757 * rather than the exact page specified by the index.
Matthew Wilcox (Oracle)2294b322020-04-01 21:05:07 -07001758 * * %FGP_CREAT - If no page is present then a new page is allocated using
1759 * @gfp_mask and added to the page cache and the VM's LRU list.
1760 * The page is returned locked and with an increased refcount.
1761 * * %FGP_FOR_MMAP - The caller wants to do its own locking dance if the
1762 * page is already in cache. If the page was allocated, unlock it before
1763 * returning so the caller can do the same dance.
Yang Shi605cad82020-08-06 23:19:58 -07001764 * * %FGP_WRITE - The page will be written
1765 * * %FGP_NOFS - __GFP_FS will get cleared in gfp mask
1766 * * %FGP_NOWAIT - Don't get blocked by page lock
mchehab@s-opensource.com0e056eb2017-03-30 17:11:36 -03001767 *
Matthew Wilcox (Oracle)2294b322020-04-01 21:05:07 -07001768 * If %FGP_LOCK or %FGP_CREAT are specified then the function may sleep even
1769 * if the %GFP flags specified for %FGP_CREAT are atomic.
Mel Gorman2457aec2014-06-04 16:10:31 -07001770 *
1771 * If there is a page cache page, it is returned with an increased refcount.
Mike Rapoporta862f682019-03-05 15:48:42 -08001772 *
Matthew Wilcox (Oracle)2294b322020-04-01 21:05:07 -07001773 * Return: The found page or %NULL otherwise.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001774 */
Matthew Wilcox (Oracle)2294b322020-04-01 21:05:07 -07001775struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
1776 int fgp_flags, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001777{
Nick Piggineb2be182007-10-16 01:24:57 -07001778 struct page *page;
Mel Gorman2457aec2014-06-04 16:10:31 -07001779
Linus Torvalds1da177e2005-04-16 15:20:36 -07001780repeat:
Matthew Wilcox (Oracle)2294b322020-04-01 21:05:07 -07001781 page = find_get_entry(mapping, index);
Matthew Wilcox3159f942017-11-03 13:30:42 -04001782 if (xa_is_value(page))
Mel Gorman2457aec2014-06-04 16:10:31 -07001783 page = NULL;
1784 if (!page)
1785 goto no_page;
1786
1787 if (fgp_flags & FGP_LOCK) {
1788 if (fgp_flags & FGP_NOWAIT) {
1789 if (!trylock_page(page)) {
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03001790 put_page(page);
Mel Gorman2457aec2014-06-04 16:10:31 -07001791 return NULL;
1792 }
1793 } else {
1794 lock_page(page);
1795 }
1796
1797 /* Has the page been truncated? */
Matthew Wilcox (Oracle)a8cf7f22020-10-13 16:51:41 -07001798 if (unlikely(page->mapping != mapping)) {
Mel Gorman2457aec2014-06-04 16:10:31 -07001799 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03001800 put_page(page);
Mel Gorman2457aec2014-06-04 16:10:31 -07001801 goto repeat;
1802 }
Matthew Wilcox (Oracle)a8cf7f22020-10-13 16:51:41 -07001803 VM_BUG_ON_PAGE(!thp_contains(page, index), page);
Mel Gorman2457aec2014-06-04 16:10:31 -07001804 }
1805
Kirill Tkhaic16eb002018-12-28 00:37:35 -08001806 if (fgp_flags & FGP_ACCESSED)
Mel Gorman2457aec2014-06-04 16:10:31 -07001807 mark_page_accessed(page);
Yang Shib9306a72020-08-06 23:19:55 -07001808 else if (fgp_flags & FGP_WRITE) {
1809 /* Clear idle flag for buffer write */
1810 if (page_is_idle(page))
1811 clear_page_idle(page);
1812 }
Matthew Wilcox (Oracle)a8cf7f22020-10-13 16:51:41 -07001813 if (!(fgp_flags & FGP_HEAD))
1814 page = find_subpage(page, index);
Mel Gorman2457aec2014-06-04 16:10:31 -07001815
1816no_page:
1817 if (!page && (fgp_flags & FGP_CREAT)) {
1818 int err;
Christoph Hellwigf56753a2020-09-24 08:51:40 +02001819 if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping))
Michal Hocko45f87de2014-12-29 20:30:35 +01001820 gfp_mask |= __GFP_WRITE;
1821 if (fgp_flags & FGP_NOFS)
1822 gfp_mask &= ~__GFP_FS;
Mel Gorman2457aec2014-06-04 16:10:31 -07001823
Michal Hocko45f87de2014-12-29 20:30:35 +01001824 page = __page_cache_alloc(gfp_mask);
Nick Piggineb2be182007-10-16 01:24:57 -07001825 if (!page)
1826 return NULL;
Mel Gorman2457aec2014-06-04 16:10:31 -07001827
Josef Bacika75d4c32019-03-13 11:44:14 -07001828 if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP))))
Mel Gorman2457aec2014-06-04 16:10:31 -07001829 fgp_flags |= FGP_LOCK;
1830
Hugh Dickinseb39d612014-08-06 16:06:43 -07001831 /* Init accessed so avoid atomic mark_page_accessed later */
Mel Gorman2457aec2014-06-04 16:10:31 -07001832 if (fgp_flags & FGP_ACCESSED)
Hugh Dickinseb39d612014-08-06 16:06:43 -07001833 __SetPageReferenced(page);
Mel Gorman2457aec2014-06-04 16:10:31 -07001834
Matthew Wilcox (Oracle)2294b322020-04-01 21:05:07 -07001835 err = add_to_page_cache_lru(page, mapping, index, gfp_mask);
Nick Piggineb2be182007-10-16 01:24:57 -07001836 if (unlikely(err)) {
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03001837 put_page(page);
Nick Piggineb2be182007-10-16 01:24:57 -07001838 page = NULL;
1839 if (err == -EEXIST)
1840 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001841 }
Josef Bacika75d4c32019-03-13 11:44:14 -07001842
1843 /*
1844 * add_to_page_cache_lru locks the page, and for mmap we expect
1845 * an unlocked page.
1846 */
1847 if (page && (fgp_flags & FGP_FOR_MMAP))
1848 unlock_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001849 }
Mel Gorman2457aec2014-06-04 16:10:31 -07001850
Linus Torvalds1da177e2005-04-16 15:20:36 -07001851 return page;
1852}
Mel Gorman2457aec2014-06-04 16:10:31 -07001853EXPORT_SYMBOL(pagecache_get_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -07001854
1855/**
Johannes Weiner0cd61442014-04-03 14:47:46 -07001856 * find_get_entries - gang pagecache lookup
1857 * @mapping: The address_space to search
1858 * @start: The starting page cache index
1859 * @nr_entries: The maximum number of entries
1860 * @entries: Where the resulting entries are placed
1861 * @indices: The cache indices corresponding to the entries in @entries
1862 *
1863 * find_get_entries() will search for and return a group of up to
1864 * @nr_entries entries in the mapping. The entries are placed at
1865 * @entries. find_get_entries() takes a reference against any actual
1866 * pages it returns.
1867 *
1868 * The search returns a group of mapping-contiguous page cache entries
1869 * with ascending indexes. There may be holes in the indices due to
1870 * not-present pages.
1871 *
Johannes Weiner139b6a62014-05-06 12:50:05 -07001872 * Any shadow entries of evicted pages, or swap entries from
1873 * shmem/tmpfs, are included in the returned array.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001874 *
Hugh Dickins71725ed2020-04-06 20:07:57 -07001875 * If it finds a Transparent Huge Page, head or tail, find_get_entries()
1876 * stops at that page: the caller is likely to have a better way to handle
1877 * the compound page as a whole, and then skip its extent, than repeatedly
1878 * calling find_get_entries() to return all its tails.
1879 *
Mike Rapoporta862f682019-03-05 15:48:42 -08001880 * Return: the number of pages and shadow entries which were found.
Johannes Weiner0cd61442014-04-03 14:47:46 -07001881 */
1882unsigned find_get_entries(struct address_space *mapping,
1883 pgoff_t start, unsigned int nr_entries,
1884 struct page **entries, pgoff_t *indices)
1885{
Matthew Wilcoxf280bf02018-05-16 17:20:45 -04001886 XA_STATE(xas, &mapping->i_pages, start);
1887 struct page *page;
Johannes Weiner0cd61442014-04-03 14:47:46 -07001888 unsigned int ret = 0;
Johannes Weiner0cd61442014-04-03 14:47:46 -07001889
1890 if (!nr_entries)
1891 return 0;
1892
1893 rcu_read_lock();
Matthew Wilcoxf280bf02018-05-16 17:20:45 -04001894 xas_for_each(&xas, page, ULONG_MAX) {
Matthew Wilcoxf280bf02018-05-16 17:20:45 -04001895 if (xas_retry(&xas, page))
Johannes Weiner0cd61442014-04-03 14:47:46 -07001896 continue;
Matthew Wilcoxf280bf02018-05-16 17:20:45 -04001897 /*
1898 * A shadow entry of a recently evicted page, a swap
1899 * entry from shmem/tmpfs or a DAX entry. Return it
1900 * without attempting to raise page count.
1901 */
1902 if (xa_is_value(page))
Johannes Weiner0cd61442014-04-03 14:47:46 -07001903 goto export;
Kirill A. Shutemov83929372016-07-26 15:26:04 -07001904
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07001905 if (!page_cache_get_speculative(page))
Matthew Wilcoxf280bf02018-05-16 17:20:45 -04001906 goto retry;
Johannes Weiner0cd61442014-04-03 14:47:46 -07001907
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07001908 /* Has the page moved or been split? */
Matthew Wilcoxf280bf02018-05-16 17:20:45 -04001909 if (unlikely(page != xas_reload(&xas)))
1910 goto put_page;
1911
Hugh Dickins71725ed2020-04-06 20:07:57 -07001912 /*
1913 * Terminate early on finding a THP, to allow the caller to
1914 * handle it all at once; but continue if this is hugetlbfs.
1915 */
1916 if (PageTransHuge(page) && !PageHuge(page)) {
1917 page = find_subpage(page, xas.xa_index);
1918 nr_entries = ret + 1;
1919 }
Johannes Weiner0cd61442014-04-03 14:47:46 -07001920export:
Matthew Wilcoxf280bf02018-05-16 17:20:45 -04001921 indices[ret] = xas.xa_index;
Johannes Weiner0cd61442014-04-03 14:47:46 -07001922 entries[ret] = page;
1923 if (++ret == nr_entries)
1924 break;
Matthew Wilcoxf280bf02018-05-16 17:20:45 -04001925 continue;
1926put_page:
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07001927 put_page(page);
Matthew Wilcoxf280bf02018-05-16 17:20:45 -04001928retry:
1929 xas_reset(&xas);
Johannes Weiner0cd61442014-04-03 14:47:46 -07001930 }
1931 rcu_read_unlock();
1932 return ret;
1933}
1934
1935/**
Jan Karab947cee2017-09-06 16:21:21 -07001936 * find_get_pages_range - gang pagecache lookup
Linus Torvalds1da177e2005-04-16 15:20:36 -07001937 * @mapping: The address_space to search
1938 * @start: The starting page index
Jan Karab947cee2017-09-06 16:21:21 -07001939 * @end: The final page index (inclusive)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001940 * @nr_pages: The maximum number of pages
1941 * @pages: Where the resulting pages are placed
1942 *
Jan Karab947cee2017-09-06 16:21:21 -07001943 * find_get_pages_range() will search for and return a group of up to @nr_pages
1944 * pages in the mapping starting at index @start and up to index @end
1945 * (inclusive). The pages are placed at @pages. find_get_pages_range() takes
1946 * a reference against the returned pages.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001947 *
1948 * The search returns a group of mapping-contiguous pages with ascending
1949 * indexes. There may be holes in the indices due to not-present pages.
Jan Karad72dc8a2017-09-06 16:21:18 -07001950 * We also update @start to index the next page for the traversal.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001951 *
Mike Rapoporta862f682019-03-05 15:48:42 -08001952 * Return: the number of pages which were found. If this number is
1953 * smaller than @nr_pages, the end of specified range has been
Jan Karab947cee2017-09-06 16:21:21 -07001954 * reached.
Linus Torvalds1da177e2005-04-16 15:20:36 -07001955 */
Jan Karab947cee2017-09-06 16:21:21 -07001956unsigned find_get_pages_range(struct address_space *mapping, pgoff_t *start,
1957 pgoff_t end, unsigned int nr_pages,
1958 struct page **pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -07001959{
Matthew Wilcoxfd1b3ce2018-05-16 17:38:56 -04001960 XA_STATE(xas, &mapping->i_pages, *start);
1961 struct page *page;
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07001962 unsigned ret = 0;
1963
1964 if (unlikely(!nr_pages))
1965 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07001966
Nick Piggina60637c2008-07-25 19:45:31 -07001967 rcu_read_lock();
Matthew Wilcoxfd1b3ce2018-05-16 17:38:56 -04001968 xas_for_each(&xas, page, end) {
Matthew Wilcoxfd1b3ce2018-05-16 17:38:56 -04001969 if (xas_retry(&xas, page))
Nick Piggina60637c2008-07-25 19:45:31 -07001970 continue;
Matthew Wilcoxfd1b3ce2018-05-16 17:38:56 -04001971 /* Skip over shadow, swap and DAX entries */
1972 if (xa_is_value(page))
Hugh Dickins8079b1c2011-08-03 16:21:28 -07001973 continue;
Nick Piggina60637c2008-07-25 19:45:31 -07001974
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07001975 if (!page_cache_get_speculative(page))
Matthew Wilcoxfd1b3ce2018-05-16 17:38:56 -04001976 goto retry;
Nick Piggina60637c2008-07-25 19:45:31 -07001977
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07001978 /* Has the page moved or been split? */
Matthew Wilcoxfd1b3ce2018-05-16 17:38:56 -04001979 if (unlikely(page != xas_reload(&xas)))
1980 goto put_page;
Nick Piggina60637c2008-07-25 19:45:31 -07001981
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07001982 pages[ret] = find_subpage(page, xas.xa_index);
Jan Karab947cee2017-09-06 16:21:21 -07001983 if (++ret == nr_pages) {
Yu Zhao5d3ee422019-03-05 15:49:17 -08001984 *start = xas.xa_index + 1;
Jan Karab947cee2017-09-06 16:21:21 -07001985 goto out;
1986 }
Matthew Wilcoxfd1b3ce2018-05-16 17:38:56 -04001987 continue;
1988put_page:
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07001989 put_page(page);
Matthew Wilcoxfd1b3ce2018-05-16 17:38:56 -04001990retry:
1991 xas_reset(&xas);
Nick Piggina60637c2008-07-25 19:45:31 -07001992 }
Hugh Dickins5b280c02011-03-22 16:33:07 -07001993
Jan Karab947cee2017-09-06 16:21:21 -07001994 /*
1995 * We come here when there is no page beyond @end. We take care to not
1996 * overflow the index @start as it confuses some of the callers. This
Matthew Wilcoxfd1b3ce2018-05-16 17:38:56 -04001997 * breaks the iteration when there is a page at index -1 but that is
Jan Karab947cee2017-09-06 16:21:21 -07001998 * already broken anyway.
1999 */
2000 if (end == (pgoff_t)-1)
2001 *start = (pgoff_t)-1;
2002 else
2003 *start = end + 1;
2004out:
Nick Piggina60637c2008-07-25 19:45:31 -07002005 rcu_read_unlock();
Jan Karad72dc8a2017-09-06 16:21:18 -07002006
Linus Torvalds1da177e2005-04-16 15:20:36 -07002007 return ret;
2008}
2009
Jens Axboeebf43502006-04-27 08:46:01 +02002010/**
2011 * find_get_pages_contig - gang contiguous pagecache lookup
2012 * @mapping: The address_space to search
2013 * @index: The starting page index
2014 * @nr_pages: The maximum number of pages
2015 * @pages: Where the resulting pages are placed
2016 *
2017 * find_get_pages_contig() works exactly like find_get_pages(), except
2018 * that the returned number of pages are guaranteed to be contiguous.
2019 *
Mike Rapoporta862f682019-03-05 15:48:42 -08002020 * Return: the number of pages which were found.
Jens Axboeebf43502006-04-27 08:46:01 +02002021 */
2022unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
2023 unsigned int nr_pages, struct page **pages)
2024{
Matthew Wilcox3ece58a2018-05-16 18:00:33 -04002025 XA_STATE(xas, &mapping->i_pages, index);
2026 struct page *page;
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07002027 unsigned int ret = 0;
2028
2029 if (unlikely(!nr_pages))
2030 return 0;
Jens Axboeebf43502006-04-27 08:46:01 +02002031
Nick Piggina60637c2008-07-25 19:45:31 -07002032 rcu_read_lock();
Matthew Wilcox3ece58a2018-05-16 18:00:33 -04002033 for (page = xas_load(&xas); page; page = xas_next(&xas)) {
Matthew Wilcox3ece58a2018-05-16 18:00:33 -04002034 if (xas_retry(&xas, page))
2035 continue;
2036 /*
2037 * If the entry has been swapped out, we can stop looking.
2038 * No current caller is looking for DAX entries.
2039 */
2040 if (xa_is_value(page))
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07002041 break;
Hugh Dickins9d8aa4e2011-03-22 16:33:06 -07002042
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07002043 if (!page_cache_get_speculative(page))
Matthew Wilcox3ece58a2018-05-16 18:00:33 -04002044 goto retry;
Nick Piggina60637c2008-07-25 19:45:31 -07002045
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07002046 /* Has the page moved or been split? */
Matthew Wilcox3ece58a2018-05-16 18:00:33 -04002047 if (unlikely(page != xas_reload(&xas)))
2048 goto put_page;
Nick Piggina60637c2008-07-25 19:45:31 -07002049
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07002050 pages[ret] = find_subpage(page, xas.xa_index);
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07002051 if (++ret == nr_pages)
2052 break;
Matthew Wilcox3ece58a2018-05-16 18:00:33 -04002053 continue;
2054put_page:
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07002055 put_page(page);
Matthew Wilcox3ece58a2018-05-16 18:00:33 -04002056retry:
2057 xas_reset(&xas);
Jens Axboeebf43502006-04-27 08:46:01 +02002058 }
Nick Piggina60637c2008-07-25 19:45:31 -07002059 rcu_read_unlock();
2060 return ret;
Jens Axboeebf43502006-04-27 08:46:01 +02002061}
David Howellsef71c152007-05-09 02:33:44 -07002062EXPORT_SYMBOL(find_get_pages_contig);
Jens Axboeebf43502006-04-27 08:46:01 +02002063
Randy Dunlap485bb992006-06-23 02:03:49 -07002064/**
Jan Kara72b045a2017-11-15 17:34:33 -08002065 * find_get_pages_range_tag - find and return pages in given range matching @tag
Randy Dunlap485bb992006-06-23 02:03:49 -07002066 * @mapping: the address_space to search
2067 * @index: the starting page index
Jan Kara72b045a2017-11-15 17:34:33 -08002068 * @end: The final page index (inclusive)
Randy Dunlap485bb992006-06-23 02:03:49 -07002069 * @tag: the tag index
2070 * @nr_pages: the maximum number of pages
2071 * @pages: where the resulting pages are placed
2072 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07002073 * Like find_get_pages, except we only return pages which are tagged with
Randy Dunlap485bb992006-06-23 02:03:49 -07002074 * @tag. We update @index to index the next page for the traversal.
Mike Rapoporta862f682019-03-05 15:48:42 -08002075 *
2076 * Return: the number of pages which were found.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002077 */
Jan Kara72b045a2017-11-15 17:34:33 -08002078unsigned find_get_pages_range_tag(struct address_space *mapping, pgoff_t *index,
Matthew Wilcoxa6906972018-05-16 18:12:54 -04002079 pgoff_t end, xa_mark_t tag, unsigned int nr_pages,
Jan Kara72b045a2017-11-15 17:34:33 -08002080 struct page **pages)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002081{
Matthew Wilcoxa6906972018-05-16 18:12:54 -04002082 XA_STATE(xas, &mapping->i_pages, *index);
2083 struct page *page;
Konstantin Khlebnikov0fc9d102012-03-28 14:42:54 -07002084 unsigned ret = 0;
2085
2086 if (unlikely(!nr_pages))
2087 return 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002088
Nick Piggina60637c2008-07-25 19:45:31 -07002089 rcu_read_lock();
Matthew Wilcoxa6906972018-05-16 18:12:54 -04002090 xas_for_each_marked(&xas, page, end, tag) {
Matthew Wilcoxa6906972018-05-16 18:12:54 -04002091 if (xas_retry(&xas, page))
Nick Piggina60637c2008-07-25 19:45:31 -07002092 continue;
Matthew Wilcoxa6906972018-05-16 18:12:54 -04002093 /*
2094 * Shadow entries should never be tagged, but this iteration
2095 * is lockless so there is a window for page reclaim to evict
2096 * a page we saw tagged. Skip over it.
2097 */
2098 if (xa_is_value(page))
Johannes Weiner139b6a62014-05-06 12:50:05 -07002099 continue;
Nick Piggina60637c2008-07-25 19:45:31 -07002100
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07002101 if (!page_cache_get_speculative(page))
Matthew Wilcoxa6906972018-05-16 18:12:54 -04002102 goto retry;
Nick Piggina60637c2008-07-25 19:45:31 -07002103
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07002104 /* Has the page moved or been split? */
Matthew Wilcoxa6906972018-05-16 18:12:54 -04002105 if (unlikely(page != xas_reload(&xas)))
2106 goto put_page;
Nick Piggina60637c2008-07-25 19:45:31 -07002107
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07002108 pages[ret] = find_subpage(page, xas.xa_index);
Jan Kara72b045a2017-11-15 17:34:33 -08002109 if (++ret == nr_pages) {
Yu Zhao5d3ee422019-03-05 15:49:17 -08002110 *index = xas.xa_index + 1;
Jan Kara72b045a2017-11-15 17:34:33 -08002111 goto out;
2112 }
Matthew Wilcoxa6906972018-05-16 18:12:54 -04002113 continue;
2114put_page:
Matthew Wilcox (Oracle)41011962019-09-23 15:34:52 -07002115 put_page(page);
Matthew Wilcoxa6906972018-05-16 18:12:54 -04002116retry:
2117 xas_reset(&xas);
Nick Piggina60637c2008-07-25 19:45:31 -07002118 }
Hugh Dickins5b280c02011-03-22 16:33:07 -07002119
Jan Kara72b045a2017-11-15 17:34:33 -08002120 /*
Matthew Wilcoxa6906972018-05-16 18:12:54 -04002121 * We come here when we got to @end. We take care to not overflow the
Jan Kara72b045a2017-11-15 17:34:33 -08002122 * index @index as it confuses some of the callers. This breaks the
Matthew Wilcoxa6906972018-05-16 18:12:54 -04002123 * iteration when there is a page at index -1 but that is already
2124 * broken anyway.
Jan Kara72b045a2017-11-15 17:34:33 -08002125 */
2126 if (end == (pgoff_t)-1)
2127 *index = (pgoff_t)-1;
2128 else
2129 *index = end + 1;
2130out:
Nick Piggina60637c2008-07-25 19:45:31 -07002131 rcu_read_unlock();
2132
Linus Torvalds1da177e2005-04-16 15:20:36 -07002133 return ret;
2134}
Jan Kara72b045a2017-11-15 17:34:33 -08002135EXPORT_SYMBOL(find_get_pages_range_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002136
Wu Fengguang76d42bd2006-06-25 05:48:43 -07002137/*
2138 * CD/DVDs are error prone. When a medium error occurs, the driver may fail
2139 * a _large_ part of the i/o request. Imagine the worst scenario:
2140 *
2141 * ---R__________________________________________B__________
2142 * ^ reading here ^ bad block(assume 4k)
2143 *
2144 * read(R) => miss => readahead(R...B) => media error => frustrating retries
2145 * => failing the whole request => read(R) => read(R+1) =>
2146 * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
2147 * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
2148 * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
2149 *
2150 * It is going insane. Fix it by quickly scaling down the readahead size.
2151 */
Souptick Joarder0f8e2db2020-04-01 21:04:50 -07002152static void shrink_readahead_size_eio(struct file_ra_state *ra)
Wu Fengguang76d42bd2006-06-25 05:48:43 -07002153{
Wu Fengguang76d42bd2006-06-25 05:48:43 -07002154 ra->ra_pages /= 4;
Wu Fengguang76d42bd2006-06-25 05:48:43 -07002155}
2156
Matthew Wilcox (Oracle)cbd59c42021-02-24 12:01:59 -08002157/*
2158 * filemap_get_read_batch - Get a batch of pages for read
2159 *
2160 * Get a batch of pages which represent a contiguous range of bytes
2161 * in the file. No tail pages will be returned. If @index is in the
2162 * middle of a THP, the entire THP will be returned. The last page in
2163 * the batch may have Readahead set or be not Uptodate so that the
2164 * caller can take the appropriate action.
2165 */
2166static void filemap_get_read_batch(struct address_space *mapping,
2167 pgoff_t index, pgoff_t max, struct pagevec *pvec)
2168{
2169 XA_STATE(xas, &mapping->i_pages, index);
2170 struct page *head;
2171
2172 rcu_read_lock();
2173 for (head = xas_load(&xas); head; head = xas_next(&xas)) {
2174 if (xas_retry(&xas, head))
2175 continue;
2176 if (xas.xa_index > max || xa_is_value(head))
2177 break;
2178 if (!page_cache_get_speculative(head))
2179 goto retry;
2180
2181 /* Has the page moved or been split? */
2182 if (unlikely(head != xas_reload(&xas)))
2183 goto put_page;
2184
2185 if (!pagevec_add(pvec, head))
2186 break;
2187 if (!PageUptodate(head))
2188 break;
2189 if (PageReadahead(head))
2190 break;
2191 xas.xa_index = head->index + thp_nr_pages(head) - 1;
2192 xas.xa_offset = (xas.xa_index >> xas.xa_shift) & XA_CHUNK_MASK;
2193 continue;
2194put_page:
2195 put_page(head);
2196retry:
2197 xas_reset(&xas);
2198 }
2199 rcu_read_unlock();
2200}
2201
Matthew Wilcox (Oracle)68430302021-02-24 12:02:15 -08002202static int filemap_read_page(struct file *file, struct address_space *mapping,
2203 struct page *page)
Kent Overstreet723ef242020-12-14 19:04:52 -08002204{
Kent Overstreet723ef242020-12-14 19:04:52 -08002205 int error;
2206
Kent Overstreet723ef242020-12-14 19:04:52 -08002207 /*
Matthew Wilcox (Oracle)68430302021-02-24 12:02:15 -08002208 * A previous I/O error may have been due to temporary failures,
2209 * eg. multipath errors. PG_error will be set again if readpage
2210 * fails.
Kent Overstreet723ef242020-12-14 19:04:52 -08002211 */
2212 ClearPageError(page);
2213 /* Start the actual read. The read will unlock the page. */
Matthew Wilcox (Oracle)68430302021-02-24 12:02:15 -08002214 error = mapping->a_ops->readpage(file, page);
2215 if (error)
2216 return error;
Kent Overstreet723ef242020-12-14 19:04:52 -08002217
Matthew Wilcox (Oracle)aa1ec2f2021-02-24 12:02:38 -08002218 error = wait_on_page_locked_killable(page);
Matthew Wilcox (Oracle)68430302021-02-24 12:02:15 -08002219 if (error)
2220 return error;
Matthew Wilcox (Oracle)aa1ec2f2021-02-24 12:02:38 -08002221 if (PageUptodate(page))
2222 return 0;
2223 if (!page->mapping) /* page truncated */
2224 return AOP_TRUNCATED_PAGE;
2225 shrink_readahead_size_eio(&file->f_ra);
2226 return -EIO;
Kent Overstreet723ef242020-12-14 19:04:52 -08002227}
2228
Matthew Wilcox (Oracle)fce70da2021-02-24 12:02:28 -08002229static bool filemap_range_uptodate(struct address_space *mapping,
2230 loff_t pos, struct iov_iter *iter, struct page *page)
2231{
2232 int count;
2233
2234 if (PageUptodate(page))
2235 return true;
2236 /* pipes can't handle partially uptodate pages */
2237 if (iov_iter_is_pipe(iter))
2238 return false;
2239 if (!mapping->a_ops->is_partially_uptodate)
2240 return false;
2241 if (mapping->host->i_blkbits >= (PAGE_SHIFT + thp_order(page)))
2242 return false;
2243
2244 count = iter->count;
2245 if (page_offset(page) > pos) {
2246 count -= page_offset(page) - pos;
2247 pos = 0;
2248 } else {
2249 pos -= page_offset(page);
2250 }
2251
2252 return mapping->a_ops->is_partially_uptodate(page, pos, count);
2253}
2254
Matthew Wilcox (Oracle)4612aee2021-02-24 12:02:22 -08002255static int filemap_update_page(struct kiocb *iocb,
2256 struct address_space *mapping, struct iov_iter *iter,
Matthew Wilcox (Oracle)fce70da2021-02-24 12:02:28 -08002257 struct page *page)
Kent Overstreet723ef242020-12-14 19:04:52 -08002258{
Kent Overstreet723ef242020-12-14 19:04:52 -08002259 int error;
2260
Matthew Wilcox (Oracle)87d1d7b2021-02-24 12:02:25 -08002261 if (!trylock_page(page)) {
2262 if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO))
2263 return -EAGAIN;
2264 if (!(iocb->ki_flags & IOCB_WAITQ)) {
Matthew Wilcox (Oracle)bd8a1f32021-02-24 12:02:05 -08002265 put_and_wait_on_page_locked(page, TASK_KILLABLE);
Matthew Wilcox (Oracle)4612aee2021-02-24 12:02:22 -08002266 return AOP_TRUNCATED_PAGE;
Matthew Wilcox (Oracle)bd8a1f32021-02-24 12:02:05 -08002267 }
Matthew Wilcox (Oracle)87d1d7b2021-02-24 12:02:25 -08002268 error = __lock_page_async(page, iocb->ki_waitq);
2269 if (error)
2270 return error;
Kent Overstreet723ef242020-12-14 19:04:52 -08002271 }
Kent Overstreet723ef242020-12-14 19:04:52 -08002272
Matthew Wilcox (Oracle)bd8a1f32021-02-24 12:02:05 -08002273 if (!page->mapping)
2274 goto truncated;
Kent Overstreet723ef242020-12-14 19:04:52 -08002275
Matthew Wilcox (Oracle)fce70da2021-02-24 12:02:28 -08002276 error = 0;
2277 if (filemap_range_uptodate(mapping, iocb->ki_pos, iter, page))
2278 goto unlock;
2279
2280 error = -EAGAIN;
2281 if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ))
2282 goto unlock;
2283
Matthew Wilcox (Oracle)68430302021-02-24 12:02:15 -08002284 error = filemap_read_page(iocb->ki_filp, mapping, page);
Matthew Wilcox (Oracle)68430302021-02-24 12:02:15 -08002285 if (error == AOP_TRUNCATED_PAGE)
Matthew Wilcox (Oracle)4612aee2021-02-24 12:02:22 -08002286 put_page(page);
2287 return error;
Matthew Wilcox (Oracle)bd8a1f32021-02-24 12:02:05 -08002288truncated:
2289 unlock_page(page);
2290 put_page(page);
Matthew Wilcox (Oracle)4612aee2021-02-24 12:02:22 -08002291 return AOP_TRUNCATED_PAGE;
Matthew Wilcox (Oracle)fce70da2021-02-24 12:02:28 -08002292unlock:
2293 unlock_page(page);
2294 return error;
Kent Overstreet723ef242020-12-14 19:04:52 -08002295}
2296
Matthew Wilcox (Oracle)f253e182021-02-24 12:02:18 -08002297static int filemap_create_page(struct file *file,
2298 struct address_space *mapping, pgoff_t index,
2299 struct pagevec *pvec)
Kent Overstreet723ef242020-12-14 19:04:52 -08002300{
Kent Overstreet723ef242020-12-14 19:04:52 -08002301 struct page *page;
2302 int error;
2303
Kent Overstreet723ef242020-12-14 19:04:52 -08002304 page = page_cache_alloc(mapping);
2305 if (!page)
Matthew Wilcox (Oracle)f253e182021-02-24 12:02:18 -08002306 return -ENOMEM;
Kent Overstreet723ef242020-12-14 19:04:52 -08002307
2308 error = add_to_page_cache_lru(page, mapping, index,
Matthew Wilcox (Oracle)f253e182021-02-24 12:02:18 -08002309 mapping_gfp_constraint(mapping, GFP_KERNEL));
2310 if (error == -EEXIST)
2311 error = AOP_TRUNCATED_PAGE;
2312 if (error)
2313 goto error;
2314
2315 error = filemap_read_page(file, mapping, page);
2316 if (error)
2317 goto error;
2318
2319 pagevec_add(pvec, page);
2320 return 0;
2321error:
Matthew Wilcox (Oracle)68430302021-02-24 12:02:15 -08002322 put_page(page);
Matthew Wilcox (Oracle)f253e182021-02-24 12:02:18 -08002323 return error;
Kent Overstreet723ef242020-12-14 19:04:52 -08002324}
2325
Matthew Wilcox (Oracle)5963fe02021-02-24 12:02:32 -08002326static int filemap_readahead(struct kiocb *iocb, struct file *file,
2327 struct address_space *mapping, struct page *page,
2328 pgoff_t last_index)
2329{
2330 if (iocb->ki_flags & IOCB_NOIO)
2331 return -EAGAIN;
2332 page_cache_async_readahead(mapping, &file->f_ra, file, page,
2333 page->index, last_index - page->index);
2334 return 0;
2335}
2336
Matthew Wilcox (Oracle)3a6bae42021-02-24 12:01:49 -08002337static int filemap_get_pages(struct kiocb *iocb, struct iov_iter *iter,
Matthew Wilcox (Oracle)ff993ba2021-02-24 12:01:55 -08002338 struct pagevec *pvec)
Kent Overstreet06c04442020-12-14 19:04:56 -08002339{
2340 struct file *filp = iocb->ki_filp;
2341 struct address_space *mapping = filp->f_mapping;
2342 struct file_ra_state *ra = &filp->f_ra;
2343 pgoff_t index = iocb->ki_pos >> PAGE_SHIFT;
Matthew Wilcox (Oracle)cbd59c42021-02-24 12:01:59 -08002344 pgoff_t last_index;
Matthew Wilcox (Oracle)2642fca2021-02-24 12:02:35 -08002345 struct page *page;
Matthew Wilcox (Oracle)cbd59c42021-02-24 12:01:59 -08002346 int err = 0;
Kent Overstreet06c04442020-12-14 19:04:56 -08002347
Matthew Wilcox (Oracle)cbd59c42021-02-24 12:01:59 -08002348 last_index = DIV_ROUND_UP(iocb->ki_pos + iter->count, PAGE_SIZE);
Matthew Wilcox (Oracle)2642fca2021-02-24 12:02:35 -08002349retry:
Kent Overstreet06c04442020-12-14 19:04:56 -08002350 if (fatal_signal_pending(current))
2351 return -EINTR;
2352
Matthew Wilcox (Oracle)cbd59c42021-02-24 12:01:59 -08002353 filemap_get_read_batch(mapping, index, last_index, pvec);
Matthew Wilcox (Oracle)2642fca2021-02-24 12:02:35 -08002354 if (!pagevec_count(pvec)) {
2355 if (iocb->ki_flags & IOCB_NOIO)
2356 return -EAGAIN;
2357 page_cache_sync_readahead(mapping, ra, filp, index,
2358 last_index - index);
2359 filemap_get_read_batch(mapping, index, last_index, pvec);
2360 }
Matthew Wilcox (Oracle)f253e182021-02-24 12:02:18 -08002361 if (!pagevec_count(pvec)) {
2362 if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
2363 return -EAGAIN;
2364 err = filemap_create_page(filp, mapping,
2365 iocb->ki_pos >> PAGE_SHIFT, pvec);
2366 if (err == AOP_TRUNCATED_PAGE)
Matthew Wilcox (Oracle)2642fca2021-02-24 12:02:35 -08002367 goto retry;
Matthew Wilcox (Oracle)f253e182021-02-24 12:02:18 -08002368 return err;
2369 }
Kent Overstreet06c04442020-12-14 19:04:56 -08002370
Matthew Wilcox (Oracle)2642fca2021-02-24 12:02:35 -08002371 page = pvec->pages[pagevec_count(pvec) - 1];
2372 if (PageReadahead(page)) {
2373 err = filemap_readahead(iocb, filp, mapping, page, last_index);
2374 if (err)
2375 goto err;
2376 }
2377 if (!PageUptodate(page)) {
2378 if ((iocb->ki_flags & IOCB_WAITQ) && pagevec_count(pvec) > 1)
2379 iocb->ki_flags |= IOCB_NOWAIT;
2380 err = filemap_update_page(iocb, mapping, iter, page);
2381 if (err)
2382 goto err;
Kent Overstreet06c04442020-12-14 19:04:56 -08002383 }
2384
Matthew Wilcox (Oracle)2642fca2021-02-24 12:02:35 -08002385 return 0;
Matthew Wilcox (Oracle)cbd59c42021-02-24 12:01:59 -08002386err:
Matthew Wilcox (Oracle)2642fca2021-02-24 12:02:35 -08002387 if (err < 0)
2388 put_page(page);
2389 if (likely(--pvec->nr))
Matthew Wilcox (Oracle)ff993ba2021-02-24 12:01:55 -08002390 return 0;
Matthew Wilcox (Oracle)4612aee2021-02-24 12:02:22 -08002391 if (err == AOP_TRUNCATED_PAGE)
Matthew Wilcox (Oracle)2642fca2021-02-24 12:02:35 -08002392 goto retry;
2393 return err;
Kent Overstreet06c04442020-12-14 19:04:56 -08002394}
2395
Randy Dunlap485bb992006-06-23 02:03:49 -07002396/**
Christoph Hellwig47c27bc2017-08-29 16:13:18 +02002397 * generic_file_buffered_read - generic file read routine
2398 * @iocb: the iocb to read
Al Viro6e58e792014-02-03 17:07:03 -05002399 * @iter: data destination
2400 * @written: already copied
Randy Dunlap485bb992006-06-23 02:03:49 -07002401 *
Linus Torvalds1da177e2005-04-16 15:20:36 -07002402 * This is a generic file read routine, and uses the
Randy Dunlap485bb992006-06-23 02:03:49 -07002403 * mapping->a_ops->readpage() function for the actual low-level stuff.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002404 *
2405 * This is really ugly. But the goto's actually try to clarify some
2406 * of the logic when it comes to error handling etc.
Mike Rapoporta862f682019-03-05 15:48:42 -08002407 *
2408 * Return:
2409 * * total number of bytes copied, including those the were already @written
2410 * * negative error code if nothing was copied
Linus Torvalds1da177e2005-04-16 15:20:36 -07002411 */
Goldwyn Rodriguesd85dc2e2019-08-30 12:09:24 -05002412ssize_t generic_file_buffered_read(struct kiocb *iocb,
Al Viro6e58e792014-02-03 17:07:03 -05002413 struct iov_iter *iter, ssize_t written)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002414{
Christoph Hellwig47c27bc2017-08-29 16:13:18 +02002415 struct file *filp = iocb->ki_filp;
Kent Overstreet06c04442020-12-14 19:04:56 -08002416 struct file_ra_state *ra = &filp->f_ra;
Christoph Hellwig36e78912008-02-08 04:21:24 -08002417 struct address_space *mapping = filp->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002418 struct inode *inode = mapping->host;
Matthew Wilcox (Oracle)ff993ba2021-02-24 12:01:55 -08002419 struct pagevec pvec;
2420 int i, error = 0;
Kent Overstreet06c04442020-12-14 19:04:56 -08002421 bool writably_mapped;
2422 loff_t isize, end_offset;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002423
Kent Overstreet723ef242020-12-14 19:04:52 -08002424 if (unlikely(iocb->ki_pos >= inode->i_sb->s_maxbytes))
Linus Torvaldsd05c5f72016-12-14 12:45:25 -08002425 return 0;
Kent Overstreet3644e2d2020-12-18 04:07:11 -05002426 if (unlikely(!iov_iter_count(iter)))
2427 return 0;
2428
Wei Fangc2a97372016-10-07 17:01:52 -07002429 iov_iter_truncate(iter, inode->i_sb->s_maxbytes);
Matthew Wilcox (Oracle)cbd59c42021-02-24 12:01:59 -08002430 pagevec_init(&pvec);
Wei Fangc2a97372016-10-07 17:01:52 -07002431
Kent Overstreet06c04442020-12-14 19:04:56 -08002432 do {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002433 cond_resched();
Kent Overstreet06c04442020-12-14 19:04:56 -08002434
2435 /*
2436 * If we've already successfully copied some data, then we
2437 * can no longer safely return -EIOCBQUEUED. Hence mark
2438 * an async read NOWAIT at that point.
2439 */
2440 if ((iocb->ki_flags & IOCB_WAITQ) && written)
2441 iocb->ki_flags |= IOCB_NOWAIT;
2442
Matthew Wilcox (Oracle)ff993ba2021-02-24 12:01:55 -08002443 error = filemap_get_pages(iocb, iter, &pvec);
2444 if (error < 0)
Kent Overstreet06c04442020-12-14 19:04:56 -08002445 break;
Michal Hocko5abf1862017-02-03 13:13:29 -08002446
Kent Overstreet723ef242020-12-14 19:04:52 -08002447 /*
Kent Overstreet06c04442020-12-14 19:04:56 -08002448 * i_size must be checked after we know the pages are Uptodate.
2449 *
2450 * Checking i_size after the check allows us to calculate
2451 * the correct value for "nr", which means the zero-filled
2452 * part of the page is not copied back to userspace (unless
2453 * another truncate extends the file - this is desired though).
Kent Overstreet723ef242020-12-14 19:04:52 -08002454 */
Kent Overstreet06c04442020-12-14 19:04:56 -08002455 isize = i_size_read(inode);
2456 if (unlikely(iocb->ki_pos >= isize))
2457 goto put_pages;
Kent Overstreet06c04442020-12-14 19:04:56 -08002458 end_offset = min_t(loff_t, isize, iocb->ki_pos + iter->count);
2459
Kent Overstreet06c04442020-12-14 19:04:56 -08002460 /*
2461 * Once we start copying data, we don't want to be touching any
2462 * cachelines that might be contended:
2463 */
2464 writably_mapped = mapping_writably_mapped(mapping);
2465
2466 /*
2467 * When a sequential read accesses a page several times, only
2468 * mark it as accessed the first time.
2469 */
2470 if (iocb->ki_pos >> PAGE_SHIFT !=
2471 ra->prev_pos >> PAGE_SHIFT)
Matthew Wilcox (Oracle)ff993ba2021-02-24 12:01:55 -08002472 mark_page_accessed(pvec.pages[0]);
Kent Overstreet06c04442020-12-14 19:04:56 -08002473
Matthew Wilcox (Oracle)ff993ba2021-02-24 12:01:55 -08002474 for (i = 0; i < pagevec_count(&pvec); i++) {
Matthew Wilcox (Oracle)cbd59c42021-02-24 12:01:59 -08002475 struct page *page = pvec.pages[i];
2476 size_t page_size = thp_size(page);
2477 size_t offset = iocb->ki_pos & (page_size - 1);
2478 size_t bytes = min_t(loff_t, end_offset - iocb->ki_pos,
2479 page_size - offset);
2480 size_t copied;
Kent Overstreet06c04442020-12-14 19:04:56 -08002481
Matthew Wilcox (Oracle)cbd59c42021-02-24 12:01:59 -08002482 if (end_offset < page_offset(page))
2483 break;
2484 if (i > 0)
2485 mark_page_accessed(page);
Kent Overstreet06c04442020-12-14 19:04:56 -08002486 /*
2487 * If users can be writing to this page using arbitrary
2488 * virtual addresses, take care about potential aliasing
2489 * before reading the page on the kernel side.
2490 */
Matthew Wilcox (Oracle)cbd59c42021-02-24 12:01:59 -08002491 if (writably_mapped) {
2492 int j;
Kent Overstreet06c04442020-12-14 19:04:56 -08002493
Matthew Wilcox (Oracle)cbd59c42021-02-24 12:01:59 -08002494 for (j = 0; j < thp_nr_pages(page); j++)
2495 flush_dcache_page(page + j);
2496 }
2497
2498 copied = copy_page_to_iter(page, offset, bytes, iter);
Kent Overstreet06c04442020-12-14 19:04:56 -08002499
2500 written += copied;
2501 iocb->ki_pos += copied;
2502 ra->prev_pos = iocb->ki_pos;
2503
2504 if (copied < bytes) {
2505 error = -EFAULT;
2506 break;
Kent Overstreet723ef242020-12-14 19:04:52 -08002507 }
Fengguang Wu3ea89ee2007-07-19 01:48:02 -07002508 }
Kent Overstreet06c04442020-12-14 19:04:56 -08002509put_pages:
Matthew Wilcox (Oracle)ff993ba2021-02-24 12:01:55 -08002510 for (i = 0; i < pagevec_count(&pvec); i++)
2511 put_page(pvec.pages[i]);
Matthew Wilcox (Oracle)cbd59c42021-02-24 12:01:59 -08002512 pagevec_reinit(&pvec);
Kent Overstreet06c04442020-12-14 19:04:56 -08002513 } while (iov_iter_count(iter) && iocb->ki_pos < isize && !error);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002514
Krishna Kumar0c6aa262008-10-15 22:01:13 -07002515 file_accessed(filp);
Kent Overstreet06c04442020-12-14 19:04:56 -08002516
Al Viro6e58e792014-02-03 17:07:03 -05002517 return written ? written : error;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002518}
Goldwyn Rodriguesd85dc2e2019-08-30 12:09:24 -05002519EXPORT_SYMBOL_GPL(generic_file_buffered_read);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002520
Randy Dunlap485bb992006-06-23 02:03:49 -07002521/**
Al Viro6abd2322014-04-04 14:20:57 -04002522 * generic_file_read_iter - generic filesystem read routine
Randy Dunlap485bb992006-06-23 02:03:49 -07002523 * @iocb: kernel I/O control block
Al Viro6abd2322014-04-04 14:20:57 -04002524 * @iter: destination for the data read
Randy Dunlap485bb992006-06-23 02:03:49 -07002525 *
Al Viro6abd2322014-04-04 14:20:57 -04002526 * This is the "read_iter()" routine for all filesystems
Linus Torvalds1da177e2005-04-16 15:20:36 -07002527 * that can use the page cache directly.
Andreas Gruenbacher41da51b2019-11-21 23:25:07 +00002528 *
2529 * The IOCB_NOWAIT flag in iocb->ki_flags indicates that -EAGAIN shall
2530 * be returned when no data can be read without waiting for I/O requests
2531 * to complete; it doesn't prevent readahead.
2532 *
2533 * The IOCB_NOIO flag in iocb->ki_flags indicates that no new I/O
2534 * requests shall be made for the read or for readahead. When no data
2535 * can be read, -EAGAIN shall be returned. When readahead would be
2536 * triggered, a partial, possibly empty read shall be returned.
2537 *
Mike Rapoporta862f682019-03-05 15:48:42 -08002538 * Return:
2539 * * number of bytes copied, even for partial reads
Andreas Gruenbacher41da51b2019-11-21 23:25:07 +00002540 * * negative error code (or 0 if IOCB_NOIO) if nothing was read
Linus Torvalds1da177e2005-04-16 15:20:36 -07002541 */
2542ssize_t
Al Viroed978a82014-03-05 22:53:04 -05002543generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002544{
Nicolai Stangee7080a42016-03-25 14:22:14 -07002545 size_t count = iov_iter_count(iter);
Christoph Hellwig47c27bc2017-08-29 16:13:18 +02002546 ssize_t retval = 0;
Nicolai Stangee7080a42016-03-25 14:22:14 -07002547
2548 if (!count)
2549 goto out; /* skip atime */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002550
Al Viro2ba48ce2015-04-09 13:52:01 -04002551 if (iocb->ki_flags & IOCB_DIRECT) {
Christoph Hellwig47c27bc2017-08-29 16:13:18 +02002552 struct file *file = iocb->ki_filp;
Al Viroed978a82014-03-05 22:53:04 -05002553 struct address_space *mapping = file->f_mapping;
2554 struct inode *inode = mapping->host;
Badari Pulavarty543ade12006-09-30 23:28:48 -07002555 loff_t size;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002556
Linus Torvalds1da177e2005-04-16 15:20:36 -07002557 size = i_size_read(inode);
Goldwyn Rodrigues6be96d32017-06-20 07:05:44 -05002558 if (iocb->ki_flags & IOCB_NOWAIT) {
2559 if (filemap_range_has_page(mapping, iocb->ki_pos,
2560 iocb->ki_pos + count - 1))
2561 return -EAGAIN;
2562 } else {
2563 retval = filemap_write_and_wait_range(mapping,
2564 iocb->ki_pos,
2565 iocb->ki_pos + count - 1);
2566 if (retval < 0)
2567 goto out;
2568 }
Al Viroed978a82014-03-05 22:53:04 -05002569
Christoph Hellwig0d5b0cf2016-10-03 09:48:08 +11002570 file_accessed(file);
2571
Al Viro5ecda132017-04-13 14:13:36 -04002572 retval = mapping->a_ops->direct_IO(iocb, iter);
Al Viroc3a69022016-10-10 13:26:27 -04002573 if (retval >= 0) {
Christoph Hellwigc64fb5c2016-04-07 08:51:55 -07002574 iocb->ki_pos += retval;
Al Viro5ecda132017-04-13 14:13:36 -04002575 count -= retval;
Steven Whitehouse9fe55ee2014-01-24 14:42:22 +00002576 }
Pavel Begunkovab2125d2021-02-24 12:01:45 -08002577 if (retval != -EIOCBQUEUED)
2578 iov_iter_revert(iter, count - iov_iter_count(iter));
Josef Bacik66f998f2010-05-23 11:00:54 -04002579
Steven Whitehouse9fe55ee2014-01-24 14:42:22 +00002580 /*
2581 * Btrfs can have a short DIO read if we encounter
2582 * compressed extents, so if there was an error, or if
2583 * we've already read everything we wanted to, or if
2584 * there was a short read because we hit EOF, go ahead
2585 * and return. Otherwise fallthrough to buffered io for
Matthew Wilcoxfbbbad42015-02-16 15:58:53 -08002586 * the rest of the read. Buffered reads will not work for
2587 * DAX files, so don't bother trying.
Steven Whitehouse9fe55ee2014-01-24 14:42:22 +00002588 */
Al Viro5ecda132017-04-13 14:13:36 -04002589 if (retval < 0 || !count || iocb->ki_pos >= size ||
Christoph Hellwig0d5b0cf2016-10-03 09:48:08 +11002590 IS_DAX(inode))
Steven Whitehouse9fe55ee2014-01-24 14:42:22 +00002591 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002592 }
2593
Christoph Hellwig47c27bc2017-08-29 16:13:18 +02002594 retval = generic_file_buffered_read(iocb, iter, retval);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002595out:
2596 return retval;
2597}
Al Viroed978a82014-03-05 22:53:04 -05002598EXPORT_SYMBOL(generic_file_read_iter);
Linus Torvalds1da177e2005-04-16 15:20:36 -07002599
Linus Torvalds1da177e2005-04-16 15:20:36 -07002600#ifdef CONFIG_MMU
Linus Torvalds1da177e2005-04-16 15:20:36 -07002601#define MMAP_LOTSAMISS (100)
Linus Torvaldsef00e082009-06-16 15:31:25 -07002602/*
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07002603 * lock_page_maybe_drop_mmap - lock the page, possibly dropping the mmap_lock
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002604 * @vmf - the vm_fault for this fault.
2605 * @page - the page to lock.
2606 * @fpin - the pointer to the file we may pin (or is already pinned).
2607 *
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07002608 * This works similar to lock_page_or_retry in that it can drop the mmap_lock.
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002609 * It differs in that it actually returns the page locked if it returns 1 and 0
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07002610 * if it couldn't lock the page. If we did have to drop the mmap_lock then fpin
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002611 * will point to the pinned file and needs to be fput()'ed at a later point.
Linus Torvaldsef00e082009-06-16 15:31:25 -07002612 */
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002613static int lock_page_maybe_drop_mmap(struct vm_fault *vmf, struct page *page,
2614 struct file **fpin)
2615{
2616 if (trylock_page(page))
2617 return 1;
2618
Linus Torvalds8b0f9fa2019-03-15 11:26:07 -07002619 /*
2620 * NOTE! This will make us return with VM_FAULT_RETRY, but with
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07002621 * the mmap_lock still held. That's how FAULT_FLAG_RETRY_NOWAIT
Linus Torvalds8b0f9fa2019-03-15 11:26:07 -07002622 * is supposed to work. We have way too many special cases..
2623 */
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002624 if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
2625 return 0;
2626
2627 *fpin = maybe_unlock_mmap_for_io(vmf, *fpin);
2628 if (vmf->flags & FAULT_FLAG_KILLABLE) {
2629 if (__lock_page_killable(page)) {
2630 /*
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07002631 * We didn't have the right flags to drop the mmap_lock,
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002632 * but all fault_handlers only check for fatal signals
2633 * if we return VM_FAULT_RETRY, so we need to drop the
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07002634 * mmap_lock here and return 0 if we don't have a fpin.
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002635 */
2636 if (*fpin == NULL)
Michel Lespinassed8ed45c2020-06-08 21:33:25 -07002637 mmap_read_unlock(vmf->vma->vm_mm);
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002638 return 0;
2639 }
2640 } else
2641 __lock_page(page);
2642 return 1;
2643}
2644
2645
2646/*
2647 * Synchronous readahead happens when we don't even find a page in the page
2648 * cache at all. We don't want to perform IO under the mmap sem, so if we have
2649 * to drop the mmap sem we return the file that was pinned in order for us to do
2650 * that. If we didn't pin a file then we return NULL. The file that is
2651 * returned needs to be fput()'ed when we're done with it.
2652 */
2653static struct file *do_sync_mmap_readahead(struct vm_fault *vmf)
Linus Torvaldsef00e082009-06-16 15:31:25 -07002654{
Josef Bacik2a1180f2019-03-13 11:44:18 -07002655 struct file *file = vmf->vma->vm_file;
2656 struct file_ra_state *ra = &file->f_ra;
Linus Torvaldsef00e082009-06-16 15:31:25 -07002657 struct address_space *mapping = file->f_mapping;
David Howellsdb660d42020-10-15 20:06:31 -07002658 DEFINE_READAHEAD(ractl, file, mapping, vmf->pgoff);
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002659 struct file *fpin = NULL;
Kirill A. Shutemove630bfa2020-08-14 17:31:27 -07002660 unsigned int mmap_miss;
Linus Torvaldsef00e082009-06-16 15:31:25 -07002661
2662 /* If we don't want any read-ahead, don't bother */
Josef Bacik2a1180f2019-03-13 11:44:18 -07002663 if (vmf->vma->vm_flags & VM_RAND_READ)
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002664 return fpin;
Wu Fengguang275b12b2011-05-24 17:12:28 -07002665 if (!ra->ra_pages)
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002666 return fpin;
Linus Torvaldsef00e082009-06-16 15:31:25 -07002667
Josef Bacik2a1180f2019-03-13 11:44:18 -07002668 if (vmf->vma->vm_flags & VM_SEQ_READ) {
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002669 fpin = maybe_unlock_mmap_for_io(vmf, fpin);
David Howellsdb660d42020-10-15 20:06:31 -07002670 page_cache_sync_ra(&ractl, ra, ra->ra_pages);
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002671 return fpin;
Linus Torvaldsef00e082009-06-16 15:31:25 -07002672 }
2673
Andi Kleen207d04b2011-05-24 17:12:29 -07002674 /* Avoid banging the cache line if not needed */
Kirill A. Shutemove630bfa2020-08-14 17:31:27 -07002675 mmap_miss = READ_ONCE(ra->mmap_miss);
2676 if (mmap_miss < MMAP_LOTSAMISS * 10)
2677 WRITE_ONCE(ra->mmap_miss, ++mmap_miss);
Linus Torvaldsef00e082009-06-16 15:31:25 -07002678
2679 /*
2680 * Do we miss much more than hit in this file? If so,
2681 * stop bothering with read-ahead. It will only hurt.
2682 */
Kirill A. Shutemove630bfa2020-08-14 17:31:27 -07002683 if (mmap_miss > MMAP_LOTSAMISS)
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002684 return fpin;
Linus Torvaldsef00e082009-06-16 15:31:25 -07002685
Wu Fengguangd30a1102009-06-16 15:31:30 -07002686 /*
2687 * mmap read-around
2688 */
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002689 fpin = maybe_unlock_mmap_for_io(vmf, fpin);
David Howellsdb660d42020-10-15 20:06:31 -07002690 ra->start = max_t(long, 0, vmf->pgoff - ra->ra_pages / 2);
Roman Gushchin600e19a2015-11-05 18:47:08 -08002691 ra->size = ra->ra_pages;
2692 ra->async_size = ra->ra_pages / 4;
David Howellsdb660d42020-10-15 20:06:31 -07002693 ractl._index = ra->start;
2694 do_page_cache_ra(&ractl, ra->size, ra->async_size);
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002695 return fpin;
Linus Torvaldsef00e082009-06-16 15:31:25 -07002696}
2697
2698/*
2699 * Asynchronous readahead happens when we find the page and PG_readahead,
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002700 * so we want to possibly extend the readahead further. We return the file that
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07002701 * was pinned if we have to drop the mmap_lock in order to do IO.
Linus Torvaldsef00e082009-06-16 15:31:25 -07002702 */
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002703static struct file *do_async_mmap_readahead(struct vm_fault *vmf,
2704 struct page *page)
Linus Torvaldsef00e082009-06-16 15:31:25 -07002705{
Josef Bacik2a1180f2019-03-13 11:44:18 -07002706 struct file *file = vmf->vma->vm_file;
2707 struct file_ra_state *ra = &file->f_ra;
Linus Torvaldsef00e082009-06-16 15:31:25 -07002708 struct address_space *mapping = file->f_mapping;
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002709 struct file *fpin = NULL;
Kirill A. Shutemove630bfa2020-08-14 17:31:27 -07002710 unsigned int mmap_miss;
Josef Bacik2a1180f2019-03-13 11:44:18 -07002711 pgoff_t offset = vmf->pgoff;
Linus Torvaldsef00e082009-06-16 15:31:25 -07002712
2713 /* If we don't want any read-ahead, don't bother */
Jan Kara5c72fee2020-04-01 21:04:40 -07002714 if (vmf->vma->vm_flags & VM_RAND_READ || !ra->ra_pages)
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002715 return fpin;
Kirill A. Shutemove630bfa2020-08-14 17:31:27 -07002716 mmap_miss = READ_ONCE(ra->mmap_miss);
2717 if (mmap_miss)
2718 WRITE_ONCE(ra->mmap_miss, --mmap_miss);
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002719 if (PageReadahead(page)) {
2720 fpin = maybe_unlock_mmap_for_io(vmf, fpin);
Wu Fengguang2fad6f52009-06-16 15:31:29 -07002721 page_cache_async_readahead(mapping, ra, file,
2722 page, offset, ra->ra_pages);
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002723 }
2724 return fpin;
Linus Torvaldsef00e082009-06-16 15:31:25 -07002725}
2726
Randy Dunlap485bb992006-06-23 02:03:49 -07002727/**
Nick Piggin54cb8822007-07-19 01:46:59 -07002728 * filemap_fault - read in file data for page fault handling
Nick Piggind0217ac2007-07-19 01:47:03 -07002729 * @vmf: struct vm_fault containing details of the fault
Randy Dunlap485bb992006-06-23 02:03:49 -07002730 *
Nick Piggin54cb8822007-07-19 01:46:59 -07002731 * filemap_fault() is invoked via the vma operations vector for a
Linus Torvalds1da177e2005-04-16 15:20:36 -07002732 * mapped memory region to read in file data during a page fault.
2733 *
2734 * The goto's are kind of ugly, but this streamlines the normal case of having
2735 * it in the page cache, and handles the special cases reasonably without
2736 * having a lot of duplicated code.
Paul Cassella9a95f3c2014-08-06 16:07:24 -07002737 *
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07002738 * vma->vm_mm->mmap_lock must be held on entry.
Paul Cassella9a95f3c2014-08-06 16:07:24 -07002739 *
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07002740 * If our return value has VM_FAULT_RETRY set, it's because the mmap_lock
Yang Shia4985832019-07-11 20:55:29 -07002741 * may be dropped before doing I/O or by lock_page_maybe_drop_mmap().
Paul Cassella9a95f3c2014-08-06 16:07:24 -07002742 *
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07002743 * If our return value does not have VM_FAULT_RETRY set, the mmap_lock
Paul Cassella9a95f3c2014-08-06 16:07:24 -07002744 * has not been released.
2745 *
2746 * We never return with VM_FAULT_RETRY and a bit from VM_FAULT_ERROR set.
Mike Rapoporta862f682019-03-05 15:48:42 -08002747 *
2748 * Return: bitwise-OR of %VM_FAULT_ codes.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002749 */
Souptick Joarder2bcd6452018-06-07 17:08:00 -07002750vm_fault_t filemap_fault(struct vm_fault *vmf)
Linus Torvalds1da177e2005-04-16 15:20:36 -07002751{
2752 int error;
Dave Jiang11bac802017-02-24 14:56:41 -08002753 struct file *file = vmf->vma->vm_file;
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002754 struct file *fpin = NULL;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002755 struct address_space *mapping = file->f_mapping;
2756 struct file_ra_state *ra = &file->f_ra;
2757 struct inode *inode = mapping->host;
Linus Torvaldsef00e082009-06-16 15:31:25 -07002758 pgoff_t offset = vmf->pgoff;
Matthew Wilcox9ab25942017-05-03 14:53:29 -07002759 pgoff_t max_off;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002760 struct page *page;
Souptick Joarder2bcd6452018-06-07 17:08:00 -07002761 vm_fault_t ret = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002762
Matthew Wilcox9ab25942017-05-03 14:53:29 -07002763 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2764 if (unlikely(offset >= max_off))
Linus Torvalds5307cc12007-10-31 09:19:46 -07002765 return VM_FAULT_SIGBUS;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002766
Linus Torvalds1da177e2005-04-16 15:20:36 -07002767 /*
Johannes Weiner49426422013-10-16 13:46:59 -07002768 * Do we have something in the page cache already?
Linus Torvalds1da177e2005-04-16 15:20:36 -07002769 */
Linus Torvaldsef00e082009-06-16 15:31:25 -07002770 page = find_get_page(mapping, offset);
Shaohua Li45cac652012-10-08 16:32:19 -07002771 if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -07002772 /*
Linus Torvaldsef00e082009-06-16 15:31:25 -07002773 * We found the page, so try async readahead before
2774 * waiting for the lock.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002775 */
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002776 fpin = do_async_mmap_readahead(vmf, page);
Shaohua Li45cac652012-10-08 16:32:19 -07002777 } else if (!page) {
Linus Torvaldsef00e082009-06-16 15:31:25 -07002778 /* No page in the page cache at all */
Linus Torvaldsef00e082009-06-16 15:31:25 -07002779 count_vm_event(PGMAJFAULT);
Roman Gushchin22621852017-07-06 15:40:25 -07002780 count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);
Linus Torvaldsef00e082009-06-16 15:31:25 -07002781 ret = VM_FAULT_MAJOR;
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002782 fpin = do_sync_mmap_readahead(vmf);
Linus Torvaldsef00e082009-06-16 15:31:25 -07002783retry_find:
Josef Bacika75d4c32019-03-13 11:44:14 -07002784 page = pagecache_get_page(mapping, offset,
2785 FGP_CREAT|FGP_FOR_MMAP,
2786 vmf->gfp_mask);
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002787 if (!page) {
2788 if (fpin)
2789 goto out_retry;
Matthew Wilcox (Oracle)e520e932020-04-01 21:04:53 -07002790 return VM_FAULT_OOM;
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002791 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07002792 }
2793
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002794 if (!lock_page_maybe_drop_mmap(vmf, page, &fpin))
2795 goto out_retry;
Michel Lespinasseb522c942010-10-26 14:21:56 -07002796
2797 /* Did it get truncated? */
Song Liu585e5a72019-09-23 15:37:44 -07002798 if (unlikely(compound_head(page)->mapping != mapping)) {
Michel Lespinasseb522c942010-10-26 14:21:56 -07002799 unlock_page(page);
2800 put_page(page);
2801 goto retry_find;
2802 }
Song Liu520e5ba2019-09-23 15:37:50 -07002803 VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page);
Michel Lespinasseb522c942010-10-26 14:21:56 -07002804
Linus Torvalds1da177e2005-04-16 15:20:36 -07002805 /*
Nick Piggind00806b2007-07-19 01:46:57 -07002806 * We have a locked page in the page cache, now we need to check
2807 * that it's up-to-date. If not, it is going to be due to an error.
Linus Torvalds1da177e2005-04-16 15:20:36 -07002808 */
Nick Piggind00806b2007-07-19 01:46:57 -07002809 if (unlikely(!PageUptodate(page)))
Linus Torvalds1da177e2005-04-16 15:20:36 -07002810 goto page_not_uptodate;
2811
Linus Torvaldsef00e082009-06-16 15:31:25 -07002812 /*
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07002813 * We've made it this far and we had to drop our mmap_lock, now is the
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002814 * time to return to the upper layer and have it re-find the vma and
2815 * redo the fault.
2816 */
2817 if (fpin) {
2818 unlock_page(page);
2819 goto out_retry;
2820 }
2821
2822 /*
Linus Torvaldsef00e082009-06-16 15:31:25 -07002823 * Found the page and have a reference on it.
2824 * We must recheck i_size under page lock.
2825 */
Matthew Wilcox9ab25942017-05-03 14:53:29 -07002826 max_off = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
2827 if (unlikely(offset >= max_off)) {
Nick Piggind00806b2007-07-19 01:46:57 -07002828 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002829 put_page(page);
Linus Torvalds5307cc12007-10-31 09:19:46 -07002830 return VM_FAULT_SIGBUS;
Nick Piggind00806b2007-07-19 01:46:57 -07002831 }
2832
Nick Piggind0217ac2007-07-19 01:47:03 -07002833 vmf->page = page;
Nick Piggin83c54072007-07-19 01:47:05 -07002834 return ret | VM_FAULT_LOCKED;
Linus Torvalds1da177e2005-04-16 15:20:36 -07002835
Linus Torvalds1da177e2005-04-16 15:20:36 -07002836page_not_uptodate:
Linus Torvalds1da177e2005-04-16 15:20:36 -07002837 /*
2838 * Umm, take care of errors if the page isn't up-to-date.
2839 * Try to re-read it _once_. We do this synchronously,
2840 * because there really aren't any performance issues here
2841 * and we need to check for errors.
2842 */
Linus Torvalds1da177e2005-04-16 15:20:36 -07002843 ClearPageError(page);
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002844 fpin = maybe_unlock_mmap_for_io(vmf, fpin);
Zach Brown994fc28c2005-12-15 14:28:17 -08002845 error = mapping->a_ops->readpage(file, page);
Miklos Szeredi3ef0f722008-05-14 16:05:37 -07002846 if (!error) {
2847 wait_on_page_locked(page);
2848 if (!PageUptodate(page))
2849 error = -EIO;
2850 }
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002851 if (fpin)
2852 goto out_retry;
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03002853 put_page(page);
Nick Piggind00806b2007-07-19 01:46:57 -07002854
2855 if (!error || error == AOP_TRUNCATED_PAGE)
2856 goto retry_find;
2857
Souptick Joarder0f8e2db2020-04-01 21:04:50 -07002858 shrink_readahead_size_eio(ra);
Nick Piggind0217ac2007-07-19 01:47:03 -07002859 return VM_FAULT_SIGBUS;
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002860
2861out_retry:
2862 /*
Michel Lespinassec1e8d7c2020-06-08 21:33:54 -07002863 * We dropped the mmap_lock, we need to return to the fault handler to
Josef Bacik6b4c9f42019-03-13 11:44:22 -07002864 * re-find the vma and come back and find our hopefully still populated
2865 * page.
2866 */
2867 if (page)
2868 put_page(page);
2869 if (fpin)
2870 fput(fpin);
2871 return ret | VM_FAULT_RETRY;
Nick Piggin54cb8822007-07-19 01:46:59 -07002872}
2873EXPORT_SYMBOL(filemap_fault);
2874
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03002875static bool filemap_map_pmd(struct vm_fault *vmf, struct page *page)
Kirill A. Shutemovf1820362014-04-07 15:37:19 -07002876{
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03002877 struct mm_struct *mm = vmf->vma->vm_mm;
2878
2879 /* Huge page is mapped? No need to proceed. */
2880 if (pmd_trans_huge(*vmf->pmd)) {
2881 unlock_page(page);
2882 put_page(page);
2883 return true;
2884 }
2885
2886 if (pmd_none(*vmf->pmd) && PageTransHuge(page)) {
2887 vm_fault_t ret = do_set_pmd(vmf, page);
2888 if (!ret) {
2889 /* The page is mapped successfully, reference consumed. */
2890 unlock_page(page);
2891 return true;
2892 }
2893 }
2894
2895 if (pmd_none(*vmf->pmd)) {
2896 vmf->ptl = pmd_lock(mm, vmf->pmd);
2897 if (likely(pmd_none(*vmf->pmd))) {
2898 mm_inc_nr_ptes(mm);
2899 pmd_populate(mm, vmf->pmd, vmf->prealloc_pte);
2900 vmf->prealloc_pte = NULL;
2901 }
2902 spin_unlock(vmf->ptl);
2903 }
2904
2905 /* See comment in handle_pte_fault() */
2906 if (pmd_devmap_trans_unstable(vmf->pmd)) {
2907 unlock_page(page);
2908 put_page(page);
2909 return true;
2910 }
2911
2912 return false;
2913}
2914
2915static struct page *next_uptodate_page(struct page *page,
2916 struct address_space *mapping,
2917 struct xa_state *xas, pgoff_t end_pgoff)
2918{
2919 unsigned long max_idx;
2920
2921 do {
2922 if (!page)
2923 return NULL;
2924 if (xas_retry(xas, page))
2925 continue;
2926 if (xa_is_value(page))
2927 continue;
2928 if (PageLocked(page))
2929 continue;
2930 if (!page_cache_get_speculative(page))
2931 continue;
2932 /* Has the page moved or been split? */
2933 if (unlikely(page != xas_reload(xas)))
2934 goto skip;
2935 if (!PageUptodate(page) || PageReadahead(page))
2936 goto skip;
2937 if (PageHWPoison(page))
2938 goto skip;
2939 if (!trylock_page(page))
2940 goto skip;
2941 if (page->mapping != mapping)
2942 goto unlock;
2943 if (!PageUptodate(page))
2944 goto unlock;
2945 max_idx = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
2946 if (xas->xa_index >= max_idx)
2947 goto unlock;
2948 return page;
2949unlock:
2950 unlock_page(page);
2951skip:
2952 put_page(page);
2953 } while ((page = xas_next_entry(xas, end_pgoff)) != NULL);
2954
2955 return NULL;
2956}
2957
2958static inline struct page *first_map_page(struct address_space *mapping,
2959 struct xa_state *xas,
2960 pgoff_t end_pgoff)
2961{
2962 return next_uptodate_page(xas_find(xas, end_pgoff),
2963 mapping, xas, end_pgoff);
2964}
2965
2966static inline struct page *next_map_page(struct address_space *mapping,
2967 struct xa_state *xas,
2968 pgoff_t end_pgoff)
2969{
2970 return next_uptodate_page(xas_next_entry(xas, end_pgoff),
2971 mapping, xas, end_pgoff);
2972}
2973
2974vm_fault_t filemap_map_pages(struct vm_fault *vmf,
2975 pgoff_t start_pgoff, pgoff_t end_pgoff)
2976{
2977 struct vm_area_struct *vma = vmf->vma;
2978 struct file *file = vma->vm_file;
Kirill A. Shutemovf1820362014-04-07 15:37:19 -07002979 struct address_space *mapping = file->f_mapping;
Kirill A. Shutemovbae473a2016-07-26 15:25:20 -07002980 pgoff_t last_pgoff = start_pgoff;
Will Deacon9d3af4b2021-01-14 15:24:19 +00002981 unsigned long addr;
Matthew Wilcox070e8072018-05-17 00:08:30 -04002982 XA_STATE(xas, &mapping->i_pages, start_pgoff);
Matthew Wilcox (Oracle)27a83a62020-10-13 16:51:44 -07002983 struct page *head, *page;
Kirill A. Shutemove630bfa2020-08-14 17:31:27 -07002984 unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss);
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03002985 vm_fault_t ret = 0;
Kirill A. Shutemovf1820362014-04-07 15:37:19 -07002986
2987 rcu_read_lock();
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03002988 head = first_map_page(mapping, &xas, end_pgoff);
2989 if (!head)
2990 goto out;
Kirill A. Shutemovf1820362014-04-07 15:37:19 -07002991
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03002992 if (filemap_map_pmd(vmf, head)) {
2993 ret = VM_FAULT_NOPAGE;
2994 goto out;
2995 }
Kirill A. Shutemovf1820362014-04-07 15:37:19 -07002996
Will Deacon9d3af4b2021-01-14 15:24:19 +00002997 addr = vma->vm_start + ((start_pgoff - vma->vm_pgoff) << PAGE_SHIFT);
2998 vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, addr, &vmf->ptl);
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03002999 do {
Matthew Wilcox (Oracle)27a83a62020-10-13 16:51:44 -07003000 page = find_subpage(head, xas.xa_index);
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03003001 if (PageHWPoison(page))
Kirill A. Shutemovf1820362014-04-07 15:37:19 -07003002 goto unlock;
3003
Kirill A. Shutemove630bfa2020-08-14 17:31:27 -07003004 if (mmap_miss > 0)
3005 mmap_miss--;
Kirill A. Shutemov7267ec002016-07-26 15:25:23 -07003006
Will Deacon9d3af4b2021-01-14 15:24:19 +00003007 addr += (xas.xa_index - last_pgoff) << PAGE_SHIFT;
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03003008 vmf->pte += xas.xa_index - last_pgoff;
Matthew Wilcox070e8072018-05-17 00:08:30 -04003009 last_pgoff = xas.xa_index;
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03003010
3011 if (!pte_none(*vmf->pte))
Kirill A. Shutemov7267ec002016-07-26 15:25:23 -07003012 goto unlock;
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03003013
Will Deacon46bdb422020-11-24 18:48:26 +00003014 /* We're about to handle the fault */
Will Deacon9d3af4b2021-01-14 15:24:19 +00003015 if (vmf->address == addr)
Will Deacon46bdb422020-11-24 18:48:26 +00003016 ret = VM_FAULT_NOPAGE;
Will Deacon46bdb422020-11-24 18:48:26 +00003017
Will Deacon9d3af4b2021-01-14 15:24:19 +00003018 do_set_pte(vmf, page, addr);
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03003019 /* no need to invalidate: a not-present page won't be cached */
Will Deacon9d3af4b2021-01-14 15:24:19 +00003020 update_mmu_cache(vma, addr, vmf->pte);
Matthew Wilcox (Oracle)27a83a62020-10-13 16:51:44 -07003021 unlock_page(head);
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03003022 continue;
Kirill A. Shutemovf1820362014-04-07 15:37:19 -07003023unlock:
Matthew Wilcox (Oracle)27a83a62020-10-13 16:51:44 -07003024 unlock_page(head);
Matthew Wilcox (Oracle)27a83a62020-10-13 16:51:44 -07003025 put_page(head);
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03003026 } while ((head = next_map_page(mapping, &xas, end_pgoff)) != NULL);
3027 pte_unmap_unlock(vmf->pte, vmf->ptl);
3028out:
Kirill A. Shutemovf1820362014-04-07 15:37:19 -07003029 rcu_read_unlock();
Kirill A. Shutemove630bfa2020-08-14 17:31:27 -07003030 WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss);
Kirill A. Shutemovf9ce0be2020-12-19 15:19:23 +03003031 return ret;
Kirill A. Shutemovf1820362014-04-07 15:37:19 -07003032}
3033EXPORT_SYMBOL(filemap_map_pages);
3034
Souptick Joarder2bcd6452018-06-07 17:08:00 -07003035vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf)
Jan Kara4fcf1c62012-06-12 16:20:29 +02003036{
Christoph Hellwig5df1a672020-11-16 14:33:37 +01003037 struct address_space *mapping = vmf->vma->vm_file->f_mapping;
Jan Kara4fcf1c62012-06-12 16:20:29 +02003038 struct page *page = vmf->page;
Souptick Joarder2bcd6452018-06-07 17:08:00 -07003039 vm_fault_t ret = VM_FAULT_LOCKED;
Jan Kara4fcf1c62012-06-12 16:20:29 +02003040
Christoph Hellwig5df1a672020-11-16 14:33:37 +01003041 sb_start_pagefault(mapping->host->i_sb);
Dave Jiang11bac802017-02-24 14:56:41 -08003042 file_update_time(vmf->vma->vm_file);
Jan Kara4fcf1c62012-06-12 16:20:29 +02003043 lock_page(page);
Christoph Hellwig5df1a672020-11-16 14:33:37 +01003044 if (page->mapping != mapping) {
Jan Kara4fcf1c62012-06-12 16:20:29 +02003045 unlock_page(page);
3046 ret = VM_FAULT_NOPAGE;
3047 goto out;
3048 }
Jan Kara14da9202012-06-12 16:20:37 +02003049 /*
3050 * We mark the page dirty already here so that when freeze is in
3051 * progress, we are guaranteed that writeback during freezing will
3052 * see the dirty page and writeprotect it again.
3053 */
3054 set_page_dirty(page);
Darrick J. Wong1d1d1a72013-02-21 16:42:51 -08003055 wait_for_stable_page(page);
Jan Kara4fcf1c62012-06-12 16:20:29 +02003056out:
Christoph Hellwig5df1a672020-11-16 14:33:37 +01003057 sb_end_pagefault(mapping->host->i_sb);
Jan Kara4fcf1c62012-06-12 16:20:29 +02003058 return ret;
3059}
Jan Kara4fcf1c62012-06-12 16:20:29 +02003060
Alexey Dobriyanf0f37e2f2009-09-27 22:29:37 +04003061const struct vm_operations_struct generic_file_vm_ops = {
Nick Piggin54cb8822007-07-19 01:46:59 -07003062 .fault = filemap_fault,
Kirill A. Shutemovf1820362014-04-07 15:37:19 -07003063 .map_pages = filemap_map_pages,
Jan Kara4fcf1c62012-06-12 16:20:29 +02003064 .page_mkwrite = filemap_page_mkwrite,
Linus Torvalds1da177e2005-04-16 15:20:36 -07003065};
3066
3067/* This is used for a general mmap of a disk file */
3068
3069int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
3070{
3071 struct address_space *mapping = file->f_mapping;
3072
3073 if (!mapping->a_ops->readpage)
3074 return -ENOEXEC;
3075 file_accessed(file);
3076 vma->vm_ops = &generic_file_vm_ops;
3077 return 0;
3078}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003079
3080/*
3081 * This is for filesystems which do not implement ->writepage.
3082 */
3083int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
3084{
3085 if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
3086 return -EINVAL;
3087 return generic_file_mmap(file, vma);
3088}
3089#else
Souptick Joarder4b96a372018-10-26 15:04:03 -07003090vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf)
Arnd Bergmann453972282018-04-13 15:35:27 -07003091{
Souptick Joarder4b96a372018-10-26 15:04:03 -07003092 return VM_FAULT_SIGBUS;
Arnd Bergmann453972282018-04-13 15:35:27 -07003093}
Linus Torvalds1da177e2005-04-16 15:20:36 -07003094int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
3095{
3096 return -ENOSYS;
3097}
3098int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
3099{
3100 return -ENOSYS;
3101}
3102#endif /* CONFIG_MMU */
3103
Arnd Bergmann453972282018-04-13 15:35:27 -07003104EXPORT_SYMBOL(filemap_page_mkwrite);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003105EXPORT_SYMBOL(generic_file_mmap);
3106EXPORT_SYMBOL(generic_file_readonly_mmap);
3107
Sasha Levin67f9fd92014-04-03 14:48:18 -07003108static struct page *wait_on_page_read(struct page *page)
3109{
3110 if (!IS_ERR(page)) {
3111 wait_on_page_locked(page);
3112 if (!PageUptodate(page)) {
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03003113 put_page(page);
Sasha Levin67f9fd92014-04-03 14:48:18 -07003114 page = ERR_PTR(-EIO);
3115 }
3116 }
3117 return page;
3118}
3119
Mel Gorman32b63522016-03-15 14:55:36 -07003120static struct page *do_read_cache_page(struct address_space *mapping,
Fengguang Wu57f6b962007-10-16 01:24:37 -07003121 pgoff_t index,
Hugh Dickins5e5358e2011-07-25 17:12:23 -07003122 int (*filler)(void *, struct page *),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003123 void *data,
3124 gfp_t gfp)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003125{
Nick Piggineb2be182007-10-16 01:24:57 -07003126 struct page *page;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003127 int err;
3128repeat:
3129 page = find_get_page(mapping, index);
3130 if (!page) {
Mel Gorman453f85d2017-11-15 17:38:03 -08003131 page = __page_cache_alloc(gfp);
Nick Piggineb2be182007-10-16 01:24:57 -07003132 if (!page)
3133 return ERR_PTR(-ENOMEM);
Dave Kleikampe6f67b82011-12-21 11:05:48 -06003134 err = add_to_page_cache_lru(page, mapping, index, gfp);
Nick Piggineb2be182007-10-16 01:24:57 -07003135 if (unlikely(err)) {
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03003136 put_page(page);
Nick Piggineb2be182007-10-16 01:24:57 -07003137 if (err == -EEXIST)
3138 goto repeat;
Matthew Wilcox22ecdb42017-12-04 04:02:00 -05003139 /* Presumably ENOMEM for xarray node */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003140 return ERR_PTR(err);
3141 }
Mel Gorman32b63522016-03-15 14:55:36 -07003142
3143filler:
Christoph Hellwig6c45b452019-07-11 20:55:20 -07003144 if (filler)
3145 err = filler(data, page);
3146 else
3147 err = mapping->a_ops->readpage(data, page);
3148
Linus Torvalds1da177e2005-04-16 15:20:36 -07003149 if (err < 0) {
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03003150 put_page(page);
Mel Gorman32b63522016-03-15 14:55:36 -07003151 return ERR_PTR(err);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003152 }
Mel Gorman32b63522016-03-15 14:55:36 -07003153
3154 page = wait_on_page_read(page);
3155 if (IS_ERR(page))
3156 return page;
3157 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003158 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003159 if (PageUptodate(page))
3160 goto out;
3161
Mel Gormanebded022016-03-15 14:55:39 -07003162 /*
Miaohe Lin0e9aa672020-10-15 20:09:58 -07003163 * Page is not up to date and may be locked due to one of the following
Mel Gormanebded022016-03-15 14:55:39 -07003164 * case a: Page is being filled and the page lock is held
3165 * case b: Read/write error clearing the page uptodate status
3166 * case c: Truncation in progress (page locked)
3167 * case d: Reclaim in progress
3168 *
3169 * Case a, the page will be up to date when the page is unlocked.
3170 * There is no need to serialise on the page lock here as the page
3171 * is pinned so the lock gives no additional protection. Even if the
Randy Dunlapce89fddf2020-08-11 18:32:53 -07003172 * page is truncated, the data is still valid if PageUptodate as
Mel Gormanebded022016-03-15 14:55:39 -07003173 * it's a race vs truncate race.
3174 * Case b, the page will not be up to date
3175 * Case c, the page may be truncated but in itself, the data may still
3176 * be valid after IO completes as it's a read vs truncate race. The
3177 * operation must restart if the page is not uptodate on unlock but
3178 * otherwise serialising on page lock to stabilise the mapping gives
3179 * no additional guarantees to the caller as the page lock is
3180 * released before return.
3181 * Case d, similar to truncation. If reclaim holds the page lock, it
3182 * will be a race with remove_mapping that determines if the mapping
3183 * is valid on unlock but otherwise the data is valid and there is
3184 * no need to serialise with page lock.
3185 *
3186 * As the page lock gives no additional guarantee, we optimistically
3187 * wait on the page to be unlocked and check if it's up to date and
3188 * use the page if it is. Otherwise, the page lock is required to
3189 * distinguish between the different cases. The motivation is that we
3190 * avoid spurious serialisations and wakeups when multiple processes
3191 * wait on the same page for IO to complete.
3192 */
3193 wait_on_page_locked(page);
3194 if (PageUptodate(page))
3195 goto out;
3196
3197 /* Distinguish between all the cases under the safety of the lock */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003198 lock_page(page);
Mel Gormanebded022016-03-15 14:55:39 -07003199
3200 /* Case c or d, restart the operation */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003201 if (!page->mapping) {
3202 unlock_page(page);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03003203 put_page(page);
Mel Gorman32b63522016-03-15 14:55:36 -07003204 goto repeat;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003205 }
Mel Gormanebded022016-03-15 14:55:39 -07003206
3207 /* Someone else locked and filled the page in a very small window */
Linus Torvalds1da177e2005-04-16 15:20:36 -07003208 if (PageUptodate(page)) {
3209 unlock_page(page);
3210 goto out;
3211 }
Xianting Tianfaffdfa2020-04-01 21:04:47 -07003212
3213 /*
3214 * A previous I/O error may have been due to temporary
3215 * failures.
3216 * Clear page error before actual read, PG_error will be
3217 * set again if read page fails.
3218 */
3219 ClearPageError(page);
Mel Gorman32b63522016-03-15 14:55:36 -07003220 goto filler;
3221
David Howellsc855ff32007-05-09 13:42:20 +01003222out:
Nick Piggin6fe69002007-05-06 14:49:04 -07003223 mark_page_accessed(page);
3224 return page;
3225}
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003226
3227/**
Sasha Levin67f9fd92014-04-03 14:48:18 -07003228 * read_cache_page - read into page cache, fill it if needed
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003229 * @mapping: the page's address_space
3230 * @index: the page index
3231 * @filler: function to perform the read
Hugh Dickins5e5358e2011-07-25 17:12:23 -07003232 * @data: first arg to filler(data, page) function, often left as NULL
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003233 *
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003234 * Read into the page cache. If a page already exists, and PageUptodate() is
Sasha Levin67f9fd92014-04-03 14:48:18 -07003235 * not set, try to fill the page and wait for it to become unlocked.
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003236 *
3237 * If the page does not get brought uptodate, return -EIO.
Mike Rapoporta862f682019-03-05 15:48:42 -08003238 *
3239 * Return: up to date page on success, ERR_PTR() on failure.
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003240 */
Sasha Levin67f9fd92014-04-03 14:48:18 -07003241struct page *read_cache_page(struct address_space *mapping,
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003242 pgoff_t index,
Hugh Dickins5e5358e2011-07-25 17:12:23 -07003243 int (*filler)(void *, struct page *),
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003244 void *data)
3245{
Christoph Hellwigd322a8e2019-07-11 20:55:17 -07003246 return do_read_cache_page(mapping, index, filler, data,
3247 mapping_gfp_mask(mapping));
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003248}
Sasha Levin67f9fd92014-04-03 14:48:18 -07003249EXPORT_SYMBOL(read_cache_page);
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003250
3251/**
3252 * read_cache_page_gfp - read into page cache, using specified page allocation flags.
3253 * @mapping: the page's address_space
3254 * @index: the page index
3255 * @gfp: the page allocator flags to use if allocating
3256 *
3257 * This is the same as "read_mapping_page(mapping, index, NULL)", but with
Dave Kleikampe6f67b82011-12-21 11:05:48 -06003258 * any new page allocations done using the specified allocation flags.
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003259 *
3260 * If the page does not get brought uptodate, return -EIO.
Mike Rapoporta862f682019-03-05 15:48:42 -08003261 *
3262 * Return: up to date page on success, ERR_PTR() on failure.
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003263 */
3264struct page *read_cache_page_gfp(struct address_space *mapping,
3265 pgoff_t index,
3266 gfp_t gfp)
3267{
Christoph Hellwig6c45b452019-07-11 20:55:20 -07003268 return do_read_cache_page(mapping, index, NULL, NULL, gfp);
Linus Torvalds0531b2a2010-01-27 09:20:03 -08003269}
3270EXPORT_SYMBOL(read_cache_page_gfp);
3271
Nick Pigginafddba42007-10-16 01:25:01 -07003272int pagecache_write_begin(struct file *file, struct address_space *mapping,
3273 loff_t pos, unsigned len, unsigned flags,
3274 struct page **pagep, void **fsdata)
3275{
3276 const struct address_space_operations *aops = mapping->a_ops;
3277
Nick Piggin4e02ed42008-10-29 14:00:55 -07003278 return aops->write_begin(file, mapping, pos, len, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07003279 pagep, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07003280}
3281EXPORT_SYMBOL(pagecache_write_begin);
3282
3283int pagecache_write_end(struct file *file, struct address_space *mapping,
3284 loff_t pos, unsigned len, unsigned copied,
3285 struct page *page, void *fsdata)
3286{
3287 const struct address_space_operations *aops = mapping->a_ops;
Nick Pigginafddba42007-10-16 01:25:01 -07003288
Nick Piggin4e02ed42008-10-29 14:00:55 -07003289 return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
Nick Pigginafddba42007-10-16 01:25:01 -07003290}
3291EXPORT_SYMBOL(pagecache_write_end);
3292
Konstantin Khlebnikova92853b2019-11-30 17:49:44 -08003293/*
3294 * Warn about a page cache invalidation failure during a direct I/O write.
3295 */
3296void dio_warn_stale_pagecache(struct file *filp)
3297{
3298 static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST);
3299 char pathname[128];
Konstantin Khlebnikova92853b2019-11-30 17:49:44 -08003300 char *path;
3301
Christoph Hellwig5df1a672020-11-16 14:33:37 +01003302 errseq_set(&filp->f_mapping->wb_err, -EIO);
Konstantin Khlebnikova92853b2019-11-30 17:49:44 -08003303 if (__ratelimit(&_rs)) {
3304 path = file_path(filp, pathname, sizeof(pathname));
3305 if (IS_ERR(path))
3306 path = "(unknown)";
3307 pr_crit("Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O!\n");
3308 pr_crit("File: %s PID: %d Comm: %.20s\n", path, current->pid,
3309 current->comm);
3310 }
3311}
3312
Linus Torvalds1da177e2005-04-16 15:20:36 -07003313ssize_t
Christoph Hellwig1af5bb42016-04-07 08:51:56 -07003314generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003315{
3316 struct file *file = iocb->ki_filp;
3317 struct address_space *mapping = file->f_mapping;
3318 struct inode *inode = mapping->host;
Christoph Hellwig1af5bb42016-04-07 08:51:56 -07003319 loff_t pos = iocb->ki_pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003320 ssize_t written;
Christoph Hellwiga969e902008-07-23 21:27:04 -07003321 size_t write_len;
3322 pgoff_t end;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003323
Al Viro0c949332014-03-22 06:51:37 -04003324 write_len = iov_iter_count(from);
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03003325 end = (pos + write_len - 1) >> PAGE_SHIFT;
Christoph Hellwiga969e902008-07-23 21:27:04 -07003326
Goldwyn Rodrigues6be96d32017-06-20 07:05:44 -05003327 if (iocb->ki_flags & IOCB_NOWAIT) {
3328 /* If there are pages to writeback, return */
Christoph Hellwig5df1a672020-11-16 14:33:37 +01003329 if (filemap_range_has_page(file->f_mapping, pos,
zhengbin35f12f02019-03-05 15:44:21 -08003330 pos + write_len - 1))
Goldwyn Rodrigues6be96d32017-06-20 07:05:44 -05003331 return -EAGAIN;
3332 } else {
3333 written = filemap_write_and_wait_range(mapping, pos,
3334 pos + write_len - 1);
3335 if (written)
3336 goto out;
3337 }
Christoph Hellwiga969e902008-07-23 21:27:04 -07003338
3339 /*
3340 * After a write we want buffered reads to be sure to go to disk to get
3341 * the new data. We invalidate clean cached page from the region we're
3342 * about to write. We do this *before* the write so that we can return
Hisashi Hifumi6ccfa802008-09-02 14:35:40 -07003343 * without clobbering -EIOCBQUEUED from ->direct_IO().
Christoph Hellwiga969e902008-07-23 21:27:04 -07003344 */
Andrey Ryabinin55635ba2017-05-03 14:55:59 -07003345 written = invalidate_inode_pages2_range(mapping,
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03003346 pos >> PAGE_SHIFT, end);
Andrey Ryabinin55635ba2017-05-03 14:55:59 -07003347 /*
3348 * If a page can not be invalidated, return 0 to fall back
3349 * to buffered write.
3350 */
3351 if (written) {
3352 if (written == -EBUSY)
3353 return 0;
3354 goto out;
Christoph Hellwiga969e902008-07-23 21:27:04 -07003355 }
3356
Al Viro639a93a52017-04-13 14:10:15 -04003357 written = mapping->a_ops->direct_IO(iocb, from);
Christoph Hellwiga969e902008-07-23 21:27:04 -07003358
3359 /*
3360 * Finally, try again to invalidate clean pages which might have been
3361 * cached by non-direct readahead, or faulted in by get_user_pages()
3362 * if the source of the write was an mmap'ed region of the file
3363 * we're writing. Either one is a pretty crazy thing to do,
3364 * so we don't support it 100%. If this invalidation
3365 * fails, tough, the write still worked...
Lukas Czerner332391a2017-09-21 08:16:29 -06003366 *
3367 * Most of the time we do not need this since dio_complete() will do
3368 * the invalidation for us. However there are some file systems that
3369 * do not end up with dio_complete() being called, so let's not break
Konstantin Khlebnikov80c1fe92019-11-30 17:49:41 -08003370 * them by removing it completely.
3371 *
Konstantin Khlebnikov9266a142019-11-30 17:49:47 -08003372 * Noticeable example is a blkdev_direct_IO().
3373 *
Konstantin Khlebnikov80c1fe92019-11-30 17:49:41 -08003374 * Skip invalidation for async writes or if mapping has no pages.
Christoph Hellwiga969e902008-07-23 21:27:04 -07003375 */
Konstantin Khlebnikov9266a142019-11-30 17:49:47 -08003376 if (written > 0 && mapping->nrpages &&
3377 invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT, end))
3378 dio_warn_stale_pagecache(file);
Christoph Hellwiga969e902008-07-23 21:27:04 -07003379
Linus Torvalds1da177e2005-04-16 15:20:36 -07003380 if (written > 0) {
Namhyung Kim01166512010-10-26 14:21:58 -07003381 pos += written;
Al Viro639a93a52017-04-13 14:10:15 -04003382 write_len -= written;
Namhyung Kim01166512010-10-26 14:21:58 -07003383 if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
3384 i_size_write(inode, pos);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003385 mark_inode_dirty(inode);
3386 }
Al Viro5cb6c6c2014-02-11 20:58:20 -05003387 iocb->ki_pos = pos;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003388 }
Pavel Begunkovab2125d2021-02-24 12:01:45 -08003389 if (written != -EIOCBQUEUED)
3390 iov_iter_revert(from, write_len - iov_iter_count(from));
Christoph Hellwiga969e902008-07-23 21:27:04 -07003391out:
Linus Torvalds1da177e2005-04-16 15:20:36 -07003392 return written;
3393}
3394EXPORT_SYMBOL(generic_file_direct_write);
3395
Nick Piggineb2be182007-10-16 01:24:57 -07003396/*
3397 * Find or create a page at the given pagecache position. Return the locked
3398 * page. This function is specifically for buffered writes.
3399 */
Nick Piggin54566b22009-01-04 12:00:53 -08003400struct page *grab_cache_page_write_begin(struct address_space *mapping,
3401 pgoff_t index, unsigned flags)
Nick Piggineb2be182007-10-16 01:24:57 -07003402{
Nick Piggineb2be182007-10-16 01:24:57 -07003403 struct page *page;
Johannes Weinerbbddabe2016-05-20 16:56:28 -07003404 int fgp_flags = FGP_LOCK|FGP_WRITE|FGP_CREAT;
Johannes Weiner0faa70c2012-01-10 15:07:53 -08003405
Nick Piggin54566b22009-01-04 12:00:53 -08003406 if (flags & AOP_FLAG_NOFS)
Mel Gorman2457aec2014-06-04 16:10:31 -07003407 fgp_flags |= FGP_NOFS;
Nick Piggineb2be182007-10-16 01:24:57 -07003408
Mel Gorman2457aec2014-06-04 16:10:31 -07003409 page = pagecache_get_page(mapping, index, fgp_flags,
Michal Hocko45f87de2014-12-29 20:30:35 +01003410 mapping_gfp_mask(mapping));
Mel Gorman2457aec2014-06-04 16:10:31 -07003411 if (page)
3412 wait_for_stable_page(page);
3413
Nick Piggineb2be182007-10-16 01:24:57 -07003414 return page;
3415}
Nick Piggin54566b22009-01-04 12:00:53 -08003416EXPORT_SYMBOL(grab_cache_page_write_begin);
Nick Piggineb2be182007-10-16 01:24:57 -07003417
Al Viro3b93f912014-02-11 21:34:08 -05003418ssize_t generic_perform_write(struct file *file,
Nick Pigginafddba42007-10-16 01:25:01 -07003419 struct iov_iter *i, loff_t pos)
3420{
3421 struct address_space *mapping = file->f_mapping;
3422 const struct address_space_operations *a_ops = mapping->a_ops;
3423 long status = 0;
3424 ssize_t written = 0;
Nick Piggin674b8922007-10-16 01:25:03 -07003425 unsigned int flags = 0;
3426
Nick Pigginafddba42007-10-16 01:25:01 -07003427 do {
3428 struct page *page;
Nick Pigginafddba42007-10-16 01:25:01 -07003429 unsigned long offset; /* Offset into pagecache page */
3430 unsigned long bytes; /* Bytes to write to page */
3431 size_t copied; /* Bytes copied from user */
3432 void *fsdata;
3433
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03003434 offset = (pos & (PAGE_SIZE - 1));
3435 bytes = min_t(unsigned long, PAGE_SIZE - offset,
Nick Pigginafddba42007-10-16 01:25:01 -07003436 iov_iter_count(i));
3437
3438again:
Linus Torvalds00a3d662015-10-07 08:32:38 +01003439 /*
3440 * Bring in the user page that we will copy from _first_.
3441 * Otherwise there's a nasty deadlock on copying from the
3442 * same page as we're writing to, without it being marked
3443 * up-to-date.
3444 *
3445 * Not only is this an optimisation, but it is also required
3446 * to check that the address is actually valid, when atomic
3447 * usercopies are used, below.
3448 */
3449 if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
3450 status = -EFAULT;
3451 break;
3452 }
3453
Jan Kara296291c2015-10-22 13:32:21 -07003454 if (fatal_signal_pending(current)) {
3455 status = -EINTR;
3456 break;
3457 }
3458
Nick Piggin674b8922007-10-16 01:25:03 -07003459 status = a_ops->write_begin(file, mapping, pos, bytes, flags,
Nick Pigginafddba42007-10-16 01:25:01 -07003460 &page, &fsdata);
Mel Gorman2457aec2014-06-04 16:10:31 -07003461 if (unlikely(status < 0))
Nick Pigginafddba42007-10-16 01:25:01 -07003462 break;
3463
anfei zhou931e80e2010-02-02 13:44:02 -08003464 if (mapping_writably_mapped(mapping))
3465 flush_dcache_page(page);
Linus Torvalds00a3d662015-10-07 08:32:38 +01003466
Nick Pigginafddba42007-10-16 01:25:01 -07003467 copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
Nick Pigginafddba42007-10-16 01:25:01 -07003468 flush_dcache_page(page);
3469
3470 status = a_ops->write_end(file, mapping, pos, bytes, copied,
3471 page, fsdata);
3472 if (unlikely(status < 0))
3473 break;
3474 copied = status;
3475
3476 cond_resched();
3477
Nick Piggin124d3b72008-02-02 15:01:17 +01003478 iov_iter_advance(i, copied);
Nick Pigginafddba42007-10-16 01:25:01 -07003479 if (unlikely(copied == 0)) {
3480 /*
3481 * If we were unable to copy any data at all, we must
3482 * fall back to a single segment length write.
3483 *
3484 * If we didn't fallback here, we could livelock
3485 * because not all segments in the iov can be copied at
3486 * once without a pagefault.
3487 */
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03003488 bytes = min_t(unsigned long, PAGE_SIZE - offset,
Nick Pigginafddba42007-10-16 01:25:01 -07003489 iov_iter_single_seg_count(i));
3490 goto again;
3491 }
Nick Pigginafddba42007-10-16 01:25:01 -07003492 pos += copied;
3493 written += copied;
3494
3495 balance_dirty_pages_ratelimited(mapping);
Nick Pigginafddba42007-10-16 01:25:01 -07003496 } while (iov_iter_count(i));
3497
3498 return written ? written : status;
3499}
Al Viro3b93f912014-02-11 21:34:08 -05003500EXPORT_SYMBOL(generic_perform_write);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003501
Jan Karae4dd9de2009-08-17 18:10:06 +02003502/**
Al Viro81742022014-04-03 03:17:43 -04003503 * __generic_file_write_iter - write data to a file
Jan Karae4dd9de2009-08-17 18:10:06 +02003504 * @iocb: IO state structure (file, offset, etc.)
Al Viro81742022014-04-03 03:17:43 -04003505 * @from: iov_iter with data to write
Jan Karae4dd9de2009-08-17 18:10:06 +02003506 *
3507 * This function does all the work needed for actually writing data to a
3508 * file. It does all basic checks, removes SUID from the file, updates
3509 * modification times and calls proper subroutines depending on whether we
3510 * do direct IO or a standard buffered write.
3511 *
3512 * It expects i_mutex to be grabbed unless we work on a block device or similar
3513 * object which does not need locking at all.
3514 *
3515 * This function does *not* take care of syncing data in case of O_SYNC write.
3516 * A caller has to handle it. This is mainly due to the fact that we want to
3517 * avoid syncing under i_mutex.
Mike Rapoporta862f682019-03-05 15:48:42 -08003518 *
3519 * Return:
3520 * * number of bytes written, even for truncated writes
3521 * * negative error code if no data has been written at all
Jan Karae4dd9de2009-08-17 18:10:06 +02003522 */
Al Viro81742022014-04-03 03:17:43 -04003523ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003524{
3525 struct file *file = iocb->ki_filp;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07003526 struct address_space * mapping = file->f_mapping;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003527 struct inode *inode = mapping->host;
Al Viro3b93f912014-02-11 21:34:08 -05003528 ssize_t written = 0;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003529 ssize_t err;
Al Viro3b93f912014-02-11 21:34:08 -05003530 ssize_t status;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003531
Linus Torvalds1da177e2005-04-16 15:20:36 -07003532 /* We can write back this queue in page reclaim */
Christoph Hellwigde1414a2015-01-14 10:42:36 +01003533 current->backing_dev_info = inode_to_bdi(inode);
Jan Kara5fa8e0a2015-05-21 16:05:53 +02003534 err = file_remove_privs(file);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003535 if (err)
3536 goto out;
3537
Josef Bacikc3b2da32012-03-26 09:59:21 -04003538 err = file_update_time(file);
3539 if (err)
3540 goto out;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003541
Al Viro2ba48ce2015-04-09 13:52:01 -04003542 if (iocb->ki_flags & IOCB_DIRECT) {
Al Viro0b8def92015-04-07 10:22:53 -04003543 loff_t pos, endbyte;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07003544
Christoph Hellwig1af5bb42016-04-07 08:51:56 -07003545 written = generic_file_direct_write(iocb, from);
Matthew Wilcoxfbbbad42015-02-16 15:58:53 -08003546 /*
3547 * If the write stopped short of completing, fall back to
3548 * buffered writes. Some filesystems do this for writes to
3549 * holes, for example. For DAX files, a buffered write will
3550 * not succeed (even if it did, DAX does not handle dirty
3551 * page-cache pages correctly).
3552 */
Al Viro0b8def92015-04-07 10:22:53 -04003553 if (written < 0 || !iov_iter_count(from) || IS_DAX(inode))
Linus Torvalds1da177e2005-04-16 15:20:36 -07003554 goto out;
Al Viro3b93f912014-02-11 21:34:08 -05003555
Al Viro0b8def92015-04-07 10:22:53 -04003556 status = generic_perform_write(file, from, pos = iocb->ki_pos);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07003557 /*
Al Viro3b93f912014-02-11 21:34:08 -05003558 * If generic_perform_write() returned a synchronous error
Jeff Moyerfb5527e2006-10-19 23:28:13 -07003559 * then we want to return the number of bytes which were
3560 * direct-written, or the error code if that was zero. Note
3561 * that this differs from normal direct-io semantics, which
3562 * will return -EFOO even if some bytes were written.
3563 */
Al Viro60bb4522014-08-08 12:39:16 -04003564 if (unlikely(status < 0)) {
Al Viro3b93f912014-02-11 21:34:08 -05003565 err = status;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07003566 goto out;
3567 }
Jeff Moyerfb5527e2006-10-19 23:28:13 -07003568 /*
3569 * We need to ensure that the page cache pages are written to
3570 * disk and invalidated to preserve the expected O_DIRECT
3571 * semantics.
3572 */
Al Viro3b93f912014-02-11 21:34:08 -05003573 endbyte = pos + status - 1;
Al Viro0b8def92015-04-07 10:22:53 -04003574 err = filemap_write_and_wait_range(mapping, pos, endbyte);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07003575 if (err == 0) {
Al Viro0b8def92015-04-07 10:22:53 -04003576 iocb->ki_pos = endbyte + 1;
Al Viro3b93f912014-02-11 21:34:08 -05003577 written += status;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07003578 invalidate_mapping_pages(mapping,
Kirill A. Shutemov09cbfea2016-04-01 15:29:47 +03003579 pos >> PAGE_SHIFT,
3580 endbyte >> PAGE_SHIFT);
Jeff Moyerfb5527e2006-10-19 23:28:13 -07003581 } else {
3582 /*
3583 * We don't know how much we wrote, so just return
3584 * the number of bytes which were direct-written
3585 */
3586 }
3587 } else {
Al Viro0b8def92015-04-07 10:22:53 -04003588 written = generic_perform_write(file, from, iocb->ki_pos);
3589 if (likely(written > 0))
3590 iocb->ki_pos += written;
Jeff Moyerfb5527e2006-10-19 23:28:13 -07003591 }
Linus Torvalds1da177e2005-04-16 15:20:36 -07003592out:
3593 current->backing_dev_info = NULL;
3594 return written ? written : err;
3595}
Al Viro81742022014-04-03 03:17:43 -04003596EXPORT_SYMBOL(__generic_file_write_iter);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003597
Jan Karae4dd9de2009-08-17 18:10:06 +02003598/**
Al Viro81742022014-04-03 03:17:43 -04003599 * generic_file_write_iter - write data to a file
Jan Karae4dd9de2009-08-17 18:10:06 +02003600 * @iocb: IO state structure
Al Viro81742022014-04-03 03:17:43 -04003601 * @from: iov_iter with data to write
Jan Karae4dd9de2009-08-17 18:10:06 +02003602 *
Al Viro81742022014-04-03 03:17:43 -04003603 * This is a wrapper around __generic_file_write_iter() to be used by most
Jan Karae4dd9de2009-08-17 18:10:06 +02003604 * filesystems. It takes care of syncing the file in case of O_SYNC file
3605 * and acquires i_mutex as needed.
Mike Rapoporta862f682019-03-05 15:48:42 -08003606 * Return:
3607 * * negative error code if no data has been written at all of
3608 * vfs_fsync_range() failed for a synchronous write
3609 * * number of bytes written, even for truncated writes
Jan Karae4dd9de2009-08-17 18:10:06 +02003610 */
Al Viro81742022014-04-03 03:17:43 -04003611ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
Linus Torvalds1da177e2005-04-16 15:20:36 -07003612{
3613 struct file *file = iocb->ki_filp;
Jan Kara148f9482009-08-17 19:52:36 +02003614 struct inode *inode = file->f_mapping->host;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003615 ssize_t ret;
Linus Torvalds1da177e2005-04-16 15:20:36 -07003616
Al Viro59551022016-01-22 15:40:57 -05003617 inode_lock(inode);
Al Viro3309dd02015-04-09 12:55:47 -04003618 ret = generic_write_checks(iocb, from);
3619 if (ret > 0)
Al Viro5f380c72015-04-07 11:28:12 -04003620 ret = __generic_file_write_iter(iocb, from);
Al Viro59551022016-01-22 15:40:57 -05003621 inode_unlock(inode);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003622
Christoph Hellwige2592212016-04-07 08:52:01 -07003623 if (ret > 0)
3624 ret = generic_write_sync(iocb, ret);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003625 return ret;
3626}
Al Viro81742022014-04-03 03:17:43 -04003627EXPORT_SYMBOL(generic_file_write_iter);
Linus Torvalds1da177e2005-04-16 15:20:36 -07003628
David Howellscf9a2ae2006-08-29 19:05:54 +01003629/**
3630 * try_to_release_page() - release old fs-specific metadata on a page
3631 *
3632 * @page: the page which the kernel is trying to free
3633 * @gfp_mask: memory allocation flags (and I/O mode)
3634 *
3635 * The address_space is to try to release any data against the page
Mike Rapoporta862f682019-03-05 15:48:42 -08003636 * (presumably at page->private).
David Howellscf9a2ae2006-08-29 19:05:54 +01003637 *
David Howells266cf652009-04-03 16:42:36 +01003638 * This may also be called if PG_fscache is set on a page, indicating that the
3639 * page is known to the local caching routines.
3640 *
David Howellscf9a2ae2006-08-29 19:05:54 +01003641 * The @gfp_mask argument specifies whether I/O may be performed to release
Mel Gorman71baba42015-11-06 16:28:28 -08003642 * this page (__GFP_IO), and whether the call may block (__GFP_RECLAIM & __GFP_FS).
David Howellscf9a2ae2006-08-29 19:05:54 +01003643 *
Mike Rapoporta862f682019-03-05 15:48:42 -08003644 * Return: %1 if the release was successful, otherwise return zero.
David Howellscf9a2ae2006-08-29 19:05:54 +01003645 */
3646int try_to_release_page(struct page *page, gfp_t gfp_mask)
3647{
3648 struct address_space * const mapping = page->mapping;
3649
3650 BUG_ON(!PageLocked(page));
3651 if (PageWriteback(page))
3652 return 0;
3653
3654 if (mapping && mapping->a_ops->releasepage)
3655 return mapping->a_ops->releasepage(page, gfp_mask);
3656 return try_to_free_buffers(page);
3657}
3658
3659EXPORT_SYMBOL(try_to_release_page);