| 1 | |
| 2 | |
| 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)
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| 12 |
|
| 13 | #include <linux/export.h>
|
| 14 | #include <linux/compiler.h>
|
| 15 | #include <linux/dax.h>
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| 16 | #include <linux/fs.h>
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| 17 | #include <linux/sched/signal.h>
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| 18 | #include <linux/uaccess.h>
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| 19 | #include <linux/capability.h>
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| 20 | #include <linux/kernel_stat.h>
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| 21 | #include <linux/gfp.h>
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| 22 | #include <linux/mm.h>
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| 23 | #include <linux/swap.h>
|
| 24 | #include <linux/swapops.h>
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| 25 | #include <linux/mman.h>
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| 26 | #include <linux/pagemap.h>
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| 27 | #include <linux/file.h>
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| 28 | #include <linux/uio.h>
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| 29 | #include <linux/error-injection.h>
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| 30 | #include <linux/hash.h>
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| 31 | #include <linux/writeback.h>
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| 32 | #include <linux/backing-dev.h>
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| 33 | #include <linux/pagevec.h>
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| 34 | #include <linux/security.h>
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| 35 | #include <linux/cpuset.h>
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| 36 | #include <linux/hugetlb.h>
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| 37 | #include <linux/memcontrol.h>
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| 38 | #include <linux/shmem_fs.h>
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| 39 | #include <linux/rmap.h>
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| 40 | #include <linux/delayacct.h>
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| 41 | #include <linux/psi.h>
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| 42 | #include <linux/ramfs.h>
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| 43 | #include <linux/page_idle.h>
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| 44 | #include <linux/migrate.h>
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| 45 | #include <linux/pipe_fs_i.h>
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| 46 | #include <linux/splice.h>
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| 47 | #include <asm/pgalloc.h>
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| 48 | #include <asm/tlbflush.h>
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| 49 | #include "internal.h"
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| 50 |
|
| 51 | #define CREATE_TRACE_POINTS
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| 52 | #include <trace/events/filemap.h>
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| 53 |
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| 54 | |
| 55 | * FIXME: remove all knowledge of the buffer layer from the core VM
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| 56 |
|
| 57 | #include <linux/buffer_head.h>
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| 58 |
|
| 59 | #include <asm/mman.h>
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| 60 |
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| 61 | |
| 62 | * Shared mappings implemented 30.11.1994. It's not fully working yet,
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| 63 | * though.
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| 64 | *
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| 65 | * Shared mappings now work. 15.8.1995 Bruno.
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| 66 | *
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| 67 | * finished 'unifying' the page and buffer cache and SMP-threaded the
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| 68 | * page-cache, 21.05.1999, Ingo Molnar <[email protected]>
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| 69 | *
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| 70 | * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <[email protected]>
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| 71 |
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| 72 |
|
| 73 | |
| 74 | * Lock ordering:
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| 75 | *
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| 76 | * ->i_mmap_rwsem (truncate_pagecache)
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| 77 | * ->private_lock (__free_pte->block_dirty_folio)
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| 78 | * ->swap_lock (exclusive_swap_page, others)
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| 79 | * ->i_pages lock
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| 80 | *
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| 81 | * ->i_rwsem
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| 82 | * ->invalidate_lock (acquired by fs in truncate path)
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| 83 | * ->i_mmap_rwsem (truncate->unmap_mapping_range)
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| 84 | *
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| 85 | * ->mmap_lock
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| 86 | * ->i_mmap_rwsem
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| 87 | * ->page_table_lock or pte_lock (various, mainly in memory.c)
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| 88 | * ->i_pages lock (arch-dependent flush_dcache_mmap_lock)
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| 89 | *
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| 90 | * ->mmap_lock
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| 91 | * ->invalidate_lock (filemap_fault)
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| 92 | * ->lock_page (filemap_fault, access_process_vm)
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| 93 | *
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| 94 | * ->i_rwsem (generic_perform_write)
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| 95 | * ->mmap_lock (fault_in_readable->do_page_fault)
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| 96 | *
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| 97 | * bdi->wb.list_lock
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| 98 | * sb_lock (fs/fs-writeback.c)
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| 99 | * ->i_pages lock (__sync_single_inode)
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| 100 | *
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| 101 | * ->i_mmap_rwsem
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| 102 | * ->anon_vma.lock (vma_merge)
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| 103 | *
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| 104 | * ->anon_vma.lock
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| 105 | * ->page_table_lock or pte_lock (anon_vma_prepare and various)
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| 106 | *
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| 107 | * ->page_table_lock or pte_lock
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| 108 | * ->swap_lock (try_to_unmap_one)
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| 109 | * ->private_lock (try_to_unmap_one)
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| 110 | * ->i_pages lock (try_to_unmap_one)
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| 111 | * ->lruvec->lru_lock (follow_page->mark_page_accessed)
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| 112 | * ->lruvec->lru_lock (check_pte_range->isolate_lru_page)
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| 113 | * ->private_lock (page_remove_rmap->set_page_dirty)
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| 114 | * ->i_pages lock (page_remove_rmap->set_page_dirty)
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| 115 | * bdi.wb->list_lock (page_remove_rmap->set_page_dirty)
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| 116 | * ->inode->i_lock (page_remove_rmap->set_page_dirty)
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| 117 | * ->memcg->move_lock (page_remove_rmap->lock_page_memcg)
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| 118 | * bdi.wb->list_lock (zap_pte_range->set_page_dirty)
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| 119 | * ->inode->i_lock (zap_pte_range->set_page_dirty)
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| 120 | * ->private_lock (zap_pte_range->block_dirty_folio)
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| 121 | *
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| 122 | * ->i_mmap_rwsem
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| 123 | * ->tasklist_lock (memory_failure, collect_procs_ao)
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| 124 |
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| 125 |
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| 126 | static void page_cache_delete(struct address_space *mapping,
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| 127 | struct folio *folio, void *shadow)
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| 128 | {
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| 129 | XA_STATE(xas, &mapping->i_pages, folio->index);
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| 130 | long nr = 1;
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| 131 |
|
| 132 | mapping_set_update(&xas, mapping);
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| 133 |
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| 134 |
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| 135 | if (!folio_test_hugetlb(folio)) {
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| 136 | xas_set_order(&xas, folio->index, folio_order(folio));
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| 137 | nr = folio_nr_pages(folio);
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| 138 | }
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| 139 |
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| 140 | VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
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| 141 |
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| 142 | xas_store(&xas, shadow);
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| 143 | xas_init_marks(&xas);
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| 144 |
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| 145 | folio->mapping = NULL;
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| 146 |
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| 147 | mapping->nrpages -= nr;
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| 148 | }
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| 149 |
|
| 150 | static void filemap_unaccount_folio(struct address_space *mapping,
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| 151 | struct folio *folio)
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| 152 | {
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| 153 | long nr;
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| 154 |
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| 155 | VM_BUG_ON_FOLIO(folio_mapped(folio), folio);
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| 156 | if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(folio_mapped(folio))) {
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| 157 | pr_alert("BUG: Bad page cache in process %s pfn:%05lx\n",
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| 158 | current->comm, folio_pfn(folio));
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| 159 | dump_page(&folio->page, "still mapped when deleted");
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| 160 | dump_stack();
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| 161 | add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
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| 162 |
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| 163 | if (mapping_exiting(mapping) && !folio_test_large(folio)) {
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| 164 | int mapcount = page_mapcount(&folio->page);
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| 165 |
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| 166 | if (folio_ref_count(folio) >= mapcount + 2) {
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| 167 | |
| 168 | * All vmas have already been torn down, so it's
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| 169 | * a good bet that actually the page is unmapped
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| 170 | * and we'd rather not leak it: if we're wrong,
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| 171 | * another bad page check should catch it later.
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| 172 |
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| 173 | page_mapcount_reset(&folio->page);
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| 174 | folio_ref_sub(folio, mapcount);
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| 175 | }
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| 176 | }
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| 177 | }
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| 178 |
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| 179 |
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| 180 | if (folio_test_hugetlb(folio))
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| 181 | return;
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| 182 |
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| 183 | nr = folio_nr_pages(folio);
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| 184 |
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| 185 | __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, -nr);
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| 186 | if (folio_test_swapbacked(folio)) {
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| 187 | __lruvec_stat_mod_folio(folio, NR_SHMEM, -nr);
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| 188 | if (folio_test_pmd_mappable(folio))
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| 189 | __lruvec_stat_mod_folio(folio, NR_SHMEM_THPS, -nr);
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| 190 | } else if (folio_test_pmd_mappable(folio)) {
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| 191 | __lruvec_stat_mod_folio(folio, NR_FILE_THPS, -nr);
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| 192 | filemap_nr_thps_dec(mapping);
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| 193 | }
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| 194 |
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| 195 | |
| 196 | * At this point folio must be either written or cleaned by
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| 197 | * truncate. Dirty folio here signals a bug and loss of
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| 198 | * unwritten data - on ordinary filesystems.
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| 199 | *
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| 200 | * But it's harmless on in-memory filesystems like tmpfs; and can
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| 201 | * occur when a driver which did get_user_pages() sets page dirty
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| 202 | * before putting it, while the inode is being finally evicted.
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| 203 | *
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| 204 | * Below fixes dirty accounting after removing the folio entirely
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| 205 | * but leaves the dirty flag set: it has no effect for truncated
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| 206 | * folio and anyway will be cleared before returning folio to
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| 207 | * buddy allocator.
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| 208 |
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| 209 | if (WARN_ON_ONCE(folio_test_dirty(folio) &&
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| 210 | mapping_can_writeback(mapping)))
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| 211 | folio_account_cleaned(folio, inode_to_wb(mapping->host));
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| 212 | }
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| 213 |
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| 214 | |
| 215 | * Delete a page from the page cache and free it. Caller has to make
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| 216 | * sure the page is locked and that nobody else uses it - or that usage
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| 217 | * is safe. The caller must hold the i_pages lock.
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| 218 |
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| 219 | void __filemap_remove_folio(struct folio *folio, void *shadow)
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| 220 | {
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| 221 | struct address_space *mapping = folio->mapping;
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| 222 |
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| 223 | trace_mm_filemap_delete_from_page_cache(folio);
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| 224 | filemap_unaccount_folio(mapping, folio);
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| 225 | page_cache_delete(mapping, folio, shadow);
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| 226 | }
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| 227 |
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| 228 | void filemap_free_folio(struct address_space *mapping, struct folio *folio)
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| 229 | {
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| 230 | void (*free_folio)(struct folio *);
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| 231 | int refs = 1;
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| 232 |
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| 233 | free_folio = mapping->a_ops->free_folio;
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| 234 | if (free_folio)
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| 235 | free_folio(folio);
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| 236 |
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| 237 | if (folio_test_large(folio) && !folio_test_hugetlb(folio))
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| 238 | refs = folio_nr_pages(folio);
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| 239 | folio_put_refs(folio, refs);
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| 240 | }
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| 241 |
|
| 242 | |
| 243 | * filemap_remove_folio - Remove folio from page cache.
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| 244 | * @folio: The folio.
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| 245 | *
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| 246 | * This must be called only on folios that are locked and have been
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| 247 | * verified to be in the page cache. It will never put the folio into
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| 248 | * the free list because the caller has a reference on the page.
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| 249 |
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| 250 | void filemap_remove_folio(struct folio *folio)
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| 251 | {
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| 252 | struct address_space *mapping = folio->mapping;
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| 253 |
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| 254 | BUG_ON(!folio_test_locked(folio));
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| 255 | spin_lock(&mapping->host->i_lock);
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| 256 | xa_lock_irq(&mapping->i_pages);
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| 257 | __filemap_remove_folio(folio, NULL);
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| 258 | xa_unlock_irq(&mapping->i_pages);
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| 259 | if (mapping_shrinkable(mapping))
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| 260 | inode_add_lru(mapping->host);
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| 261 | spin_unlock(&mapping->host->i_lock);
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| 262 |
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| 263 | filemap_free_folio(mapping, folio);
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| 264 | }
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| 265 |
|
| 266 | |
| 267 | * page_cache_delete_batch - delete several folios from page cache
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| 268 | * @mapping: the mapping to which folios belong
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| 269 | * @fbatch: batch of folios to delete
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| 270 | *
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| 271 | * The function walks over mapping->i_pages and removes folios passed in
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| 272 | * @fbatch from the mapping. The function expects @fbatch to be sorted
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| 273 | * by page index and is optimised for it to be dense.
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| 274 | * It tolerates holes in @fbatch (mapping entries at those indices are not
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| 275 | * modified).
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| 276 | *
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| 277 | * The function expects the i_pages lock to be held.
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| 278 |
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| 279 | static void page_cache_delete_batch(struct address_space *mapping,
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| 280 | struct folio_batch *fbatch)
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| 281 | {
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| 282 | XA_STATE(xas, &mapping->i_pages, fbatch->folios[0]->index);
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| 283 | long total_pages = 0;
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| 284 | int i = 0;
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| 285 | struct folio *folio;
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| 286 |
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| 287 | mapping_set_update(&xas, mapping);
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| 288 | xas_for_each(&xas, folio, ULONG_MAX) {
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| 289 | if (i >= folio_batch_count(fbatch))
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| 290 | break;
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| 291 |
|
| 292 |
|
| 293 | if (xa_is_value(folio))
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| 294 | continue;
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| 295 | |
| 296 | * A page got inserted in our range? Skip it. We have our
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| 297 | * pages locked so they are protected from being removed.
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| 298 | * If we see a page whose index is higher than ours, it
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| 299 | * means our page has been removed, which shouldn't be
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| 300 | * possible because we're holding the PageLock.
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| 301 |
|
| 302 | if (folio != fbatch->folios[i]) {
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| 303 | VM_BUG_ON_FOLIO(folio->index >
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| 304 | fbatch->folios[i]->index, folio);
|
| 305 | continue;
|
| 306 | }
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| 307 |
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| 308 | WARN_ON_ONCE(!folio_test_locked(folio));
|
| 309 |
|
| 310 | folio->mapping = NULL;
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| 311 |
|
| 312 |
|
| 313 | i++;
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| 314 | xas_store(&xas, NULL);
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| 315 | total_pages += folio_nr_pages(folio);
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| 316 | }
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| 317 | mapping->nrpages -= total_pages;
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| 318 | }
|
| 319 |
|
| 320 | void delete_from_page_cache_batch(struct address_space *mapping,
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| 321 | struct folio_batch *fbatch)
|
| 322 | {
|
| 323 | int i;
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| 324 |
|
| 325 | if (!folio_batch_count(fbatch))
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| 326 | return;
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| 327 |
|
| 328 | spin_lock(&mapping->host->i_lock);
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| 329 | xa_lock_irq(&mapping->i_pages);
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| 330 | for (i = 0; i < folio_batch_count(fbatch); i++) {
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| 331 | struct folio *folio = fbatch->folios[i];
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| 332 |
|
| 333 | trace_mm_filemap_delete_from_page_cache(folio);
|
| 334 | filemap_unaccount_folio(mapping, folio);
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| 335 | }
|
| 336 | page_cache_delete_batch(mapping, fbatch);
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| 337 | xa_unlock_irq(&mapping->i_pages);
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| 338 | if (mapping_shrinkable(mapping))
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| 339 | inode_add_lru(mapping->host);
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| 340 | spin_unlock(&mapping->host->i_lock);
|
| 341 |
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| 342 | for (i = 0; i < folio_batch_count(fbatch); i++)
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| 343 | filemap_free_folio(mapping, fbatch->folios[i]);
|
| 344 | }
|
| 345 |
|
| 346 | int filemap_check_errors(struct address_space *mapping)
|
| 347 | {
|
| 348 | int ret = 0;
|
| 349 |
|
| 350 | if (test_bit(AS_ENOSPC, &mapping->flags) &&
|
| 351 | test_and_clear_bit(AS_ENOSPC, &mapping->flags))
|
| 352 | ret = -ENOSPC;
|
| 353 | if (test_bit(AS_EIO, &mapping->flags) &&
|
| 354 | test_and_clear_bit(AS_EIO, &mapping->flags))
|
| 355 | ret = -EIO;
|
| 356 | return ret;
|
| 357 | }
|
| 358 | EXPORT_SYMBOL(filemap_check_errors);
|
| 359 |
|
| 360 | static int filemap_check_and_keep_errors(struct address_space *mapping)
|
| 361 | {
|
| 362 |
|
| 363 | if (test_bit(AS_EIO, &mapping->flags))
|
| 364 | return -EIO;
|
| 365 | if (test_bit(AS_ENOSPC, &mapping->flags))
|
| 366 | return -ENOSPC;
|
| 367 | return 0;
|
| 368 | }
|
| 369 |
|
| 370 | |
| 371 | * filemap_fdatawrite_wbc - start writeback on mapping dirty pages in range
|
| 372 | * @mapping: address space structure to write
|
| 373 | * @wbc: the writeback_control controlling the writeout
|
| 374 | *
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| 375 | * Call writepages on the mapping using the provided wbc to control the
|
| 376 | * writeout.
|
| 377 | *
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| 378 | * Return: %0 on success, negative error code otherwise.
|
| 379 |
|
| 380 | int filemap_fdatawrite_wbc(struct address_space *mapping,
|
| 381 | struct writeback_control *wbc)
|
| 382 | {
|
| 383 | int ret;
|
| 384 |
|
| 385 | if (!mapping_can_writeback(mapping) ||
|
| 386 | !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
|
| 387 | return 0;
|
| 388 |
|
| 389 | wbc_attach_fdatawrite_inode(wbc, mapping->host);
|
| 390 | ret = do_writepages(mapping, wbc);
|
| 391 | wbc_detach_inode(wbc);
|
| 392 | return ret;
|
| 393 | }
|
| 394 | EXPORT_SYMBOL(filemap_fdatawrite_wbc);
|
| 395 |
|
| 396 | |
| 397 | * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
|
| 398 | * @mapping: address space structure to write
|
| 399 | * @start: offset in bytes where the range starts
|
| 400 | * @end: offset in bytes where the range ends (inclusive)
|
| 401 | * @sync_mode: enable synchronous operation
|
| 402 | *
|
| 403 | * Start writeback against all of a mapping's dirty pages that lie
|
| 404 | * within the byte offsets <start, end> inclusive.
|
| 405 | *
|
| 406 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
|
| 407 | * opposed to a regular memory cleansing writeback. The difference between
|
| 408 | * these two operations is that if a dirty page/buffer is encountered, it must
|
| 409 | * be waited upon, and not just skipped over.
|
| 410 | *
|
| 411 | * Return: %0 on success, negative error code otherwise.
|
| 412 |
|
| 413 | int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
|
| 414 | loff_t end, int sync_mode)
|
| 415 | {
|
| 416 | struct writeback_control wbc = {
|
| 417 | .sync_mode = sync_mode,
|
| 418 | .nr_to_write = LONG_MAX,
|
| 419 | .range_start = start,
|
| 420 | .range_end = end,
|
| 421 | };
|
| 422 |
|
| 423 | return filemap_fdatawrite_wbc(mapping, &wbc);
|
| 424 | }
|
| 425 |
|
| 426 | static inline int __filemap_fdatawrite(struct address_space *mapping,
|
| 427 | int sync_mode)
|
| 428 | {
|
| 429 | return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
|
| 430 | }
|
| 431 |
|
| 432 | int filemap_fdatawrite(struct address_space *mapping)
|
| 433 | {
|
| 434 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
|
| 435 | }
|
| 436 | EXPORT_SYMBOL(filemap_fdatawrite);
|
| 437 |
|
| 438 | int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
|
| 439 | loff_t end)
|
| 440 | {
|
| 441 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
|
| 442 | }
|
| 443 | EXPORT_SYMBOL(filemap_fdatawrite_range);
|
| 444 |
|
| 445 | |
| 446 | * filemap_flush - mostly a non-blocking flush
|
| 447 | * @mapping: target address_space
|
| 448 | *
|
| 449 | * This is a mostly non-blocking flush. Not suitable for data-integrity
|
| 450 | * purposes - I/O may not be started against all dirty pages.
|
| 451 | *
|
| 452 | * Return: %0 on success, negative error code otherwise.
|
| 453 |
|
| 454 | int filemap_flush(struct address_space *mapping)
|
| 455 | {
|
| 456 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
|
| 457 | }
|
| 458 | EXPORT_SYMBOL(filemap_flush);
|
| 459 |
|
| 460 | |
| 461 | * filemap_range_has_page - check if a page exists in range.
|
| 462 | * @mapping: address space within which to check
|
| 463 | * @start_byte: offset in bytes where the range starts
|
| 464 | * @end_byte: offset in bytes where the range ends (inclusive)
|
| 465 | *
|
| 466 | * Find at least one page in the range supplied, usually used to check if
|
| 467 | * direct writing in this range will trigger a writeback.
|
| 468 | *
|
| 469 | * Return: %true if at least one page exists in the specified range,
|
| 470 | * %false otherwise.
|
| 471 |
|
| 472 | bool filemap_range_has_page(struct address_space *mapping,
|
| 473 | loff_t start_byte, loff_t end_byte)
|
| 474 | {
|
| 475 | struct folio *folio;
|
| 476 | XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT);
|
| 477 | pgoff_t max = end_byte >> PAGE_SHIFT;
|
| 478 |
|
| 479 | if (end_byte < start_byte)
|
| 480 | return false;
|
| 481 |
|
| 482 | rcu_read_lock();
|
| 483 | for (;;) {
|
| 484 | folio = xas_find(&xas, max);
|
| 485 | if (xas_retry(&xas, folio))
|
| 486 | continue;
|
| 487 |
|
| 488 | if (xa_is_value(folio))
|
| 489 | continue;
|
| 490 | |
| 491 | * We don't need to try to pin this page; we're about to
|
| 492 | * release the RCU lock anyway. It is enough to know that
|
| 493 | * there was a page here recently.
|
| 494 |
|
| 495 | break;
|
| 496 | }
|
| 497 | rcu_read_unlock();
|
| 498 |
|
| 499 | return folio != NULL;
|
| 500 | }
|
| 501 | EXPORT_SYMBOL(filemap_range_has_page);
|
| 502 |
|
| 503 | static void __filemap_fdatawait_range(struct address_space *mapping,
|
| 504 | loff_t start_byte, loff_t end_byte)
|
| 505 | {
|
| 506 | pgoff_t index = start_byte >> PAGE_SHIFT;
|
| 507 | pgoff_t end = end_byte >> PAGE_SHIFT;
|
| 508 | struct folio_batch fbatch;
|
| 509 | unsigned nr_folios;
|
| 510 |
|
| 511 | folio_batch_init(&fbatch);
|
| 512 |
|
| 513 | while (index <= end) {
|
| 514 | unsigned i;
|
| 515 |
|
| 516 | nr_folios = filemap_get_folios_tag(mapping, &index, end,
|
| 517 | PAGECACHE_TAG_WRITEBACK, &fbatch);
|
| 518 |
|
| 519 | if (!nr_folios)
|
| 520 | break;
|
| 521 |
|
| 522 | for (i = 0; i < nr_folios; i++) {
|
| 523 | struct folio *folio = fbatch.folios[i];
|
| 524 |
|
| 525 | folio_wait_writeback(folio);
|
| 526 | folio_clear_error(folio);
|
| 527 | }
|
| 528 | folio_batch_release(&fbatch);
|
| 529 | cond_resched();
|
| 530 | }
|
| 531 | }
|
| 532 |
|
| 533 | |
| 534 | * filemap_fdatawait_range - wait for writeback to complete
|
| 535 | * @mapping: address space structure to wait for
|
| 536 | * @start_byte: offset in bytes where the range starts
|
| 537 | * @end_byte: offset in bytes where the range ends (inclusive)
|
| 538 | *
|
| 539 | * Walk the list of under-writeback pages of the given address space
|
| 540 | * in the given range and wait for all of them. Check error status of
|
| 541 | * the address space and return it.
|
| 542 | *
|
| 543 | * Since the error status of the address space is cleared by this function,
|
| 544 | * callers are responsible for checking the return value and handling and/or
|
| 545 | * reporting the error.
|
| 546 | *
|
| 547 | * Return: error status of the address space.
|
| 548 |
|
| 549 | int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
|
| 550 | loff_t end_byte)
|
| 551 | {
|
| 552 | __filemap_fdatawait_range(mapping, start_byte, end_byte);
|
| 553 | return filemap_check_errors(mapping);
|
| 554 | }
|
| 555 | EXPORT_SYMBOL(filemap_fdatawait_range);
|
| 556 |
|
| 557 | |
| 558 | * filemap_fdatawait_range_keep_errors - wait for writeback to complete
|
| 559 | * @mapping: address space structure to wait for
|
| 560 | * @start_byte: offset in bytes where the range starts
|
| 561 | * @end_byte: offset in bytes where the range ends (inclusive)
|
| 562 | *
|
| 563 | * Walk the list of under-writeback pages of the given address space in the
|
| 564 | * given range and wait for all of them. Unlike filemap_fdatawait_range(),
|
| 565 | * this function does not clear error status of the address space.
|
| 566 | *
|
| 567 | * Use this function if callers don't handle errors themselves. Expected
|
| 568 | * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2),
|
| 569 | * fsfreeze(8)
|
| 570 |
|
| 571 | int filemap_fdatawait_range_keep_errors(struct address_space *mapping,
|
| 572 | loff_t start_byte, loff_t end_byte)
|
| 573 | {
|
| 574 | __filemap_fdatawait_range(mapping, start_byte, end_byte);
|
| 575 | return filemap_check_and_keep_errors(mapping);
|
| 576 | }
|
| 577 | EXPORT_SYMBOL(filemap_fdatawait_range_keep_errors);
|
| 578 |
|
| 579 | |
| 580 | * file_fdatawait_range - wait for writeback to complete
|
| 581 | * @file: file pointing to address space structure to wait for
|
| 582 | * @start_byte: offset in bytes where the range starts
|
| 583 | * @end_byte: offset in bytes where the range ends (inclusive)
|
| 584 | *
|
| 585 | * Walk the list of under-writeback pages of the address space that file
|
| 586 | * refers to, in the given range and wait for all of them. Check error
|
| 587 | * status of the address space vs. the file->f_wb_err cursor and return it.
|
| 588 | *
|
| 589 | * Since the error status of the file is advanced by this function,
|
| 590 | * callers are responsible for checking the return value and handling and/or
|
| 591 | * reporting the error.
|
| 592 | *
|
| 593 | * Return: error status of the address space vs. the file->f_wb_err cursor.
|
| 594 |
|
| 595 | int file_fdatawait_range(struct file *file, loff_t start_byte, loff_t end_byte)
|
| 596 | {
|
| 597 | struct address_space *mapping = file->f_mapping;
|
| 598 |
|
| 599 | __filemap_fdatawait_range(mapping, start_byte, end_byte);
|
| 600 | return file_check_and_advance_wb_err(file);
|
| 601 | }
|
| 602 | EXPORT_SYMBOL(file_fdatawait_range);
|
| 603 |
|
| 604 | |
| 605 | * filemap_fdatawait_keep_errors - wait for writeback without clearing errors
|
| 606 | * @mapping: address space structure to wait for
|
| 607 | *
|
| 608 | * Walk the list of under-writeback pages of the given address space
|
| 609 | * and wait for all of them. Unlike filemap_fdatawait(), this function
|
| 610 | * does not clear error status of the address space.
|
| 611 | *
|
| 612 | * Use this function if callers don't handle errors themselves. Expected
|
| 613 | * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2),
|
| 614 | * fsfreeze(8)
|
| 615 | *
|
| 616 | * Return: error status of the address space.
|
| 617 |
|
| 618 | int filemap_fdatawait_keep_errors(struct address_space *mapping)
|
| 619 | {
|
| 620 | __filemap_fdatawait_range(mapping, 0, LLONG_MAX);
|
| 621 | return filemap_check_and_keep_errors(mapping);
|
| 622 | }
|
| 623 | EXPORT_SYMBOL(filemap_fdatawait_keep_errors);
|
| 624 |
|
| 625 |
|
| 626 | static bool mapping_needs_writeback(struct address_space *mapping)
|
| 627 | {
|
| 628 | return mapping->nrpages;
|
| 629 | }
|
| 630 |
|
| 631 | bool filemap_range_has_writeback(struct address_space *mapping,
|
| 632 | loff_t start_byte, loff_t end_byte)
|
| 633 | {
|
| 634 | XA_STATE(xas, &mapping->i_pages, start_byte >> PAGE_SHIFT);
|
| 635 | pgoff_t max = end_byte >> PAGE_SHIFT;
|
| 636 | struct folio *folio;
|
| 637 |
|
| 638 | if (end_byte < start_byte)
|
| 639 | return false;
|
| 640 |
|
| 641 | rcu_read_lock();
|
| 642 | xas_for_each(&xas, folio, max) {
|
| 643 | if (xas_retry(&xas, folio))
|
| 644 | continue;
|
| 645 | if (xa_is_value(folio))
|
| 646 | continue;
|
| 647 | if (folio_test_dirty(folio) || folio_test_locked(folio) ||
|
| 648 | folio_test_writeback(folio))
|
| 649 | break;
|
| 650 | }
|
| 651 | rcu_read_unlock();
|
| 652 | return folio != NULL;
|
| 653 | }
|
| 654 | EXPORT_SYMBOL_GPL(filemap_range_has_writeback);
|
| 655 |
|
| 656 | |
| 657 | * filemap_write_and_wait_range - write out & wait on a file range
|
| 658 | * @mapping: the address_space for the pages
|
| 659 | * @lstart: offset in bytes where the range starts
|
| 660 | * @lend: offset in bytes where the range ends (inclusive)
|
| 661 | *
|
| 662 | * Write out and wait upon file offsets lstart->lend, inclusive.
|
| 663 | *
|
| 664 | * Note that @lend is inclusive (describes the last byte to be written) so
|
| 665 | * that this function can be used to write to the very end-of-file (end = -1).
|
| 666 | *
|
| 667 | * Return: error status of the address space.
|
| 668 |
|
| 669 | int filemap_write_and_wait_range(struct address_space *mapping,
|
| 670 | loff_t lstart, loff_t lend)
|
| 671 | {
|
| 672 | int err = 0, err2;
|
| 673 |
|
| 674 | if (lend < lstart)
|
| 675 | return 0;
|
| 676 |
|
| 677 | if (mapping_needs_writeback(mapping)) {
|
| 678 | err = __filemap_fdatawrite_range(mapping, lstart, lend,
|
| 679 | WB_SYNC_ALL);
|
| 680 | |
| 681 | * Even if the above returned error, the pages may be
|
| 682 | * written partially (e.g. -ENOSPC), so we wait for it.
|
| 683 | * But the -EIO is special case, it may indicate the worst
|
| 684 | * thing (e.g. bug) happened, so we avoid waiting for it.
|
| 685 |
|
| 686 | if (err != -EIO)
|
| 687 | __filemap_fdatawait_range(mapping, lstart, lend);
|
| 688 | }
|
| 689 | err2 = filemap_check_errors(mapping);
|
| 690 | if (!err)
|
| 691 | err = err2;
|
| 692 | return err;
|
| 693 | }
|
| 694 | EXPORT_SYMBOL(filemap_write_and_wait_range);
|
| 695 |
|
| 696 | void __filemap_set_wb_err(struct address_space *mapping, int err)
|
| 697 | {
|
| 698 | errseq_t eseq = errseq_set(&mapping->wb_err, err);
|
| 699 |
|
| 700 | trace_filemap_set_wb_err(mapping, eseq);
|
| 701 | }
|
| 702 | EXPORT_SYMBOL(__filemap_set_wb_err);
|
| 703 |
|
| 704 | |
| 705 | * file_check_and_advance_wb_err - report wb error (if any) that was previously
|
| 706 | * and advance wb_err to current one
|
| 707 | * @file: struct file on which the error is being reported
|
| 708 | *
|
| 709 | * When userland calls fsync (or something like nfsd does the equivalent), we
|
| 710 | * want to report any writeback errors that occurred since the last fsync (or
|
| 711 | * since the file was opened if there haven't been any).
|
| 712 | *
|
| 713 | * Grab the wb_err from the mapping. If it matches what we have in the file,
|
| 714 | * then just quickly return 0. The file is all caught up.
|
| 715 | *
|
| 716 | * If it doesn't match, then take the mapping value, set the "seen" flag in
|
| 717 | * it and try to swap it into place. If it works, or another task beat us
|
| 718 | * to it with the new value, then update the f_wb_err and return the error
|
| 719 | * portion. The error at this point must be reported via proper channels
|
| 720 | * (a'la fsync, or NFS COMMIT operation, etc.).
|
| 721 | *
|
| 722 | * While we handle mapping->wb_err with atomic operations, the f_wb_err
|
| 723 | * value is protected by the f_lock since we must ensure that it reflects
|
| 724 | * the latest value swapped in for this file descriptor.
|
| 725 | *
|
| 726 | * Return: %0 on success, negative error code otherwise.
|
| 727 |
|
| 728 | int file_check_and_advance_wb_err(struct file *file)
|
| 729 | {
|
| 730 | int err = 0;
|
| 731 | errseq_t old = READ_ONCE(file->f_wb_err);
|
| 732 | struct address_space *mapping = file->f_mapping;
|
| 733 |
|
| 734 |
|
| 735 | if (errseq_check(&mapping->wb_err, old)) {
|
| 736 |
|
| 737 | spin_lock(&file->f_lock);
|
| 738 | old = file->f_wb_err;
|
| 739 | err = errseq_check_and_advance(&mapping->wb_err,
|
| 740 | &file->f_wb_err);
|
| 741 | trace_file_check_and_advance_wb_err(file, old);
|
| 742 | spin_unlock(&file->f_lock);
|
| 743 | }
|
| 744 |
|
| 745 | |
| 746 | * We're mostly using this function as a drop in replacement for
|
| 747 | * filemap_check_errors. Clear AS_EIO/AS_ENOSPC to emulate the effect
|
| 748 | * that the legacy code would have had on these flags.
|
| 749 |
|
| 750 | clear_bit(AS_EIO, &mapping->flags);
|
| 751 | clear_bit(AS_ENOSPC, &mapping->flags);
|
| 752 | return err;
|
| 753 | }
|
| 754 | EXPORT_SYMBOL(file_check_and_advance_wb_err);
|
| 755 |
|
| 756 | |
| 757 | * file_write_and_wait_range - write out & wait on a file range
|
| 758 | * @file: file pointing to address_space with pages
|
| 759 | * @lstart: offset in bytes where the range starts
|
| 760 | * @lend: offset in bytes where the range ends (inclusive)
|
| 761 | *
|
| 762 | * Write out and wait upon file offsets lstart->lend, inclusive.
|
| 763 | *
|
| 764 | * Note that @lend is inclusive (describes the last byte to be written) so
|
| 765 | * that this function can be used to write to the very end-of-file (end = -1).
|
| 766 | *
|
| 767 | * After writing out and waiting on the data, we check and advance the
|
| 768 | * f_wb_err cursor to the latest value, and return any errors detected there.
|
| 769 | *
|
| 770 | * Return: %0 on success, negative error code otherwise.
|
| 771 |
|
| 772 | int file_write_and_wait_range(struct file *file, loff_t lstart, loff_t lend)
|
| 773 | {
|
| 774 | int err = 0, err2;
|
| 775 | struct address_space *mapping = file->f_mapping;
|
| 776 |
|
| 777 | if (lend < lstart)
|
| 778 | return 0;
|
| 779 |
|
| 780 | if (mapping_needs_writeback(mapping)) {
|
| 781 | err = __filemap_fdatawrite_range(mapping, lstart, lend,
|
| 782 | WB_SYNC_ALL);
|
| 783 |
|
| 784 | if (err != -EIO)
|
| 785 | __filemap_fdatawait_range(mapping, lstart, lend);
|
| 786 | }
|
| 787 | err2 = file_check_and_advance_wb_err(file);
|
| 788 | if (!err)
|
| 789 | err = err2;
|
| 790 | return err;
|
| 791 | }
|
| 792 | EXPORT_SYMBOL(file_write_and_wait_range);
|
| 793 |
|
| 794 | |
| 795 | * replace_page_cache_folio - replace a pagecache folio with a new one
|
| 796 | * @old: folio to be replaced
|
| 797 | * @new: folio to replace with
|
| 798 | *
|
| 799 | * This function replaces a folio in the pagecache with a new one. On
|
| 800 | * success it acquires the pagecache reference for the new folio and
|
| 801 | * drops it for the old folio. Both the old and new folios must be
|
| 802 | * locked. This function does not add the new folio to the LRU, the
|
| 803 | * caller must do that.
|
| 804 | *
|
| 805 | * The remove + add is atomic. This function cannot fail.
|
| 806 |
|
| 807 | void replace_page_cache_folio(struct folio *old, struct folio *new)
|
| 808 | {
|
| 809 | struct address_space *mapping = old->mapping;
|
| 810 | void (*free_folio)(struct folio *) = mapping->a_ops->free_folio;
|
| 811 | pgoff_t offset = old->index;
|
| 812 | XA_STATE(xas, &mapping->i_pages, offset);
|
| 813 |
|
| 814 | VM_BUG_ON_FOLIO(!folio_test_locked(old), old);
|
| 815 | VM_BUG_ON_FOLIO(!folio_test_locked(new), new);
|
| 816 | VM_BUG_ON_FOLIO(new->mapping, new);
|
| 817 |
|
| 818 | folio_get(new);
|
| 819 | new->mapping = mapping;
|
| 820 | new->index = offset;
|
| 821 |
|
| 822 | mem_cgroup_migrate(old, new);
|
| 823 |
|
| 824 | xas_lock_irq(&xas);
|
| 825 | xas_store(&xas, new);
|
| 826 |
|
| 827 | old->mapping = NULL;
|
| 828 |
|
| 829 | if (!folio_test_hugetlb(old))
|
| 830 | __lruvec_stat_sub_folio(old, NR_FILE_PAGES);
|
| 831 | if (!folio_test_hugetlb(new))
|
| 832 | __lruvec_stat_add_folio(new, NR_FILE_PAGES);
|
| 833 | if (folio_test_swapbacked(old))
|
| 834 | __lruvec_stat_sub_folio(old, NR_SHMEM);
|
| 835 | if (folio_test_swapbacked(new))
|
| 836 | __lruvec_stat_add_folio(new, NR_SHMEM);
|
| 837 | xas_unlock_irq(&xas);
|
| 838 | if (free_folio)
|
| 839 | free_folio(old);
|
| 840 | folio_put(old);
|
| 841 | }
|
| 842 | EXPORT_SYMBOL_GPL(replace_page_cache_folio);
|
| 843 |
|
| 844 | noinline int __filemap_add_folio(struct address_space *mapping,
|
| 845 | struct folio *folio, pgoff_t index, gfp_t gfp, void **shadowp)
|
| 846 | {
|
| 847 | XA_STATE(xas, &mapping->i_pages, index);
|
| 848 | int huge = folio_test_hugetlb(folio);
|
| 849 | bool charged = false;
|
| 850 | long nr = 1;
|
| 851 |
|
| 852 | VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
|
| 853 | VM_BUG_ON_FOLIO(folio_test_swapbacked(folio), folio);
|
| 854 | mapping_set_update(&xas, mapping);
|
| 855 |
|
| 856 | if (!huge) {
|
| 857 | int error = mem_cgroup_charge(folio, NULL, gfp);
|
| 858 | VM_BUG_ON_FOLIO(index & (folio_nr_pages(folio) - 1), folio);
|
| 859 | if (error)
|
| 860 | return error;
|
| 861 | charged = true;
|
| 862 | xas_set_order(&xas, index, folio_order(folio));
|
| 863 | nr = folio_nr_pages(folio);
|
| 864 | }
|
| 865 |
|
| 866 | gfp &= GFP_RECLAIM_MASK;
|
| 867 | folio_ref_add(folio, nr);
|
| 868 | folio->mapping = mapping;
|
| 869 | folio->index = xas.xa_index;
|
| 870 |
|
| 871 | do {
|
| 872 | unsigned int order = xa_get_order(xas.xa, xas.xa_index);
|
| 873 | void *entry, *old = NULL;
|
| 874 |
|
| 875 | if (order > folio_order(folio))
|
| 876 | xas_split_alloc(&xas, xa_load(xas.xa, xas.xa_index),
|
| 877 | order, gfp);
|
| 878 | xas_lock_irq(&xas);
|
| 879 | xas_for_each_conflict(&xas, entry) {
|
| 880 | old = entry;
|
| 881 | if (!xa_is_value(entry)) {
|
| 882 | xas_set_err(&xas, -EEXIST);
|
| 883 | goto unlock;
|
| 884 | }
|
| 885 | }
|
| 886 |
|
| 887 | if (old) {
|
| 888 | if (shadowp)
|
| 889 | *shadowp = old;
|
| 890 |
|
| 891 | order = xa_get_order(xas.xa, xas.xa_index);
|
| 892 | if (order > folio_order(folio)) {
|
| 893 |
|
| 894 | BUG_ON(shmem_mapping(mapping));
|
| 895 | xas_split(&xas, old, order);
|
| 896 | xas_reset(&xas);
|
| 897 | }
|
| 898 | }
|
| 899 |
|
| 900 | xas_store(&xas, folio);
|
| 901 | if (xas_error(&xas))
|
| 902 | goto unlock;
|
| 903 |
|
| 904 | mapping->nrpages += nr;
|
| 905 |
|
| 906 |
|
| 907 | if (!huge) {
|
| 908 | __lruvec_stat_mod_folio(folio, NR_FILE_PAGES, nr);
|
| 909 | if (folio_test_pmd_mappable(folio))
|
| 910 | __lruvec_stat_mod_folio(folio,
|
| 911 | NR_FILE_THPS, nr);
|
| 912 | }
|
| 913 | unlock:
|
| 914 | xas_unlock_irq(&xas);
|
| 915 | } while (xas_nomem(&xas, gfp));
|
| 916 |
|
| 917 | if (xas_error(&xas))
|
| 918 | goto error;
|
| 919 |
|
| 920 | trace_mm_filemap_add_to_page_cache(folio);
|
| 921 | return 0;
|
| 922 | error:
|
| 923 | if (charged)
|
| 924 | mem_cgroup_uncharge(folio);
|
| 925 | folio->mapping = NULL;
|
| 926 |
|
| 927 | folio_put_refs(folio, nr);
|
| 928 | return xas_error(&xas);
|
| 929 | }
|
| 930 | ALLOW_ERROR_INJECTION(__filemap_add_folio, ERRNO);
|
| 931 |
|
| 932 | int filemap_add_folio(struct address_space *mapping, struct folio *folio,
|
| 933 | pgoff_t index, gfp_t gfp)
|
| 934 | {
|
| 935 | void *shadow = NULL;
|
| 936 | int ret;
|
| 937 |
|
| 938 | __folio_set_locked(folio);
|
| 939 | ret = __filemap_add_folio(mapping, folio, index, gfp, &shadow);
|
| 940 | if (unlikely(ret))
|
| 941 | __folio_clear_locked(folio);
|
| 942 | else {
|
| 943 | |
| 944 | * The folio might have been evicted from cache only
|
| 945 | * recently, in which case it should be activated like
|
| 946 | * any other repeatedly accessed folio.
|
| 947 | * The exception is folios getting rewritten; evicting other
|
| 948 | * data from the working set, only to cache data that will
|
| 949 | * get overwritten with something else, is a waste of memory.
|
| 950 |
|
| 951 | WARN_ON_ONCE(folio_test_active(folio));
|
| 952 | if (!(gfp & __GFP_WRITE) && shadow)
|
| 953 | workingset_refault(folio, shadow);
|
| 954 | folio_add_lru(folio);
|
| 955 | }
|
| 956 | return ret;
|
| 957 | }
|
| 958 | EXPORT_SYMBOL_GPL(filemap_add_folio);
|
| 959 |
|
| 960 | #ifdef CONFIG_NUMA
|
| 961 | struct folio *filemap_alloc_folio(gfp_t gfp, unsigned int order)
|
| 962 | {
|
| 963 | int n;
|
| 964 | struct folio *folio;
|
| 965 |
|
| 966 | if (cpuset_do_page_mem_spread()) {
|
| 967 | unsigned int cpuset_mems_cookie;
|
| 968 | do {
|
| 969 | cpuset_mems_cookie = read_mems_allowed_begin();
|
| 970 | n = cpuset_mem_spread_node();
|
| 971 | folio = __folio_alloc_node(gfp, order, n);
|
| 972 | } while (!folio && read_mems_allowed_retry(cpuset_mems_cookie));
|
| 973 |
|
| 974 | return folio;
|
| 975 | }
|
| 976 | return folio_alloc(gfp, order);
|
| 977 | }
|
| 978 | EXPORT_SYMBOL(filemap_alloc_folio);
|
| 979 | #endif
|
| 980 |
|
| 981 | |
| 982 | * filemap_invalidate_lock_two - lock invalidate_lock for two mappings
|
| 983 | *
|
| 984 | * Lock exclusively invalidate_lock of any passed mapping that is not NULL.
|
| 985 | *
|
| 986 | * @mapping1: the first mapping to lock
|
| 987 | * @mapping2: the second mapping to lock
|
| 988 |
|
| 989 | void filemap_invalidate_lock_two(struct address_space *mapping1,
|
| 990 | struct address_space *mapping2)
|
| 991 | {
|
| 992 | if (mapping1 > mapping2)
|
| 993 | swap(mapping1, mapping2);
|
| 994 | if (mapping1)
|
| 995 | down_write(&mapping1->invalidate_lock);
|
| 996 | if (mapping2 && mapping1 != mapping2)
|
| 997 | down_write_nested(&mapping2->invalidate_lock, 1);
|
| 998 | }
|
| 999 | EXPORT_SYMBOL(filemap_invalidate_lock_two);
|
| 1000 |
|
| 1001 | |
| 1002 | * filemap_invalidate_unlock_two - unlock invalidate_lock for two mappings
|
| 1003 | *
|
| 1004 | * Unlock exclusive invalidate_lock of any passed mapping that is not NULL.
|
| 1005 | *
|
| 1006 | * @mapping1: the first mapping to unlock
|
| 1007 | * @mapping2: the second mapping to unlock
|
| 1008 |
|
| 1009 | void filemap_invalidate_unlock_two(struct address_space *mapping1,
|
| 1010 | struct address_space *mapping2)
|
| 1011 | {
|
| 1012 | if (mapping1)
|
| 1013 | up_write(&mapping1->invalidate_lock);
|
| 1014 | if (mapping2 && mapping1 != mapping2)
|
| 1015 | up_write(&mapping2->invalidate_lock);
|
| 1016 | }
|
| 1017 | EXPORT_SYMBOL(filemap_invalidate_unlock_two);
|
| 1018 |
|
| 1019 | |
| 1020 | * In order to wait for pages to become available there must be
|
| 1021 | * waitqueues associated with pages. By using a hash table of
|
| 1022 | * waitqueues where the bucket discipline is to maintain all
|
| 1023 | * waiters on the same queue and wake all when any of the pages
|
| 1024 | * become available, and for the woken contexts to check to be
|
| 1025 | * sure the appropriate page became available, this saves space
|
| 1026 | * at a cost of "thundering herd" phenomena during rare hash
|
| 1027 | * collisions.
|
| 1028 |
|
| 1029 | #define PAGE_WAIT_TABLE_BITS 8
|
| 1030 | #define PAGE_WAIT_TABLE_SIZE (1 << PAGE_WAIT_TABLE_BITS)
|
| 1031 | static wait_queue_head_t folio_wait_table[PAGE_WAIT_TABLE_SIZE] __cacheline_aligned;
|
| 1032 |
|
| 1033 | static wait_queue_head_t *folio_waitqueue(struct folio *folio)
|
| 1034 | {
|
| 1035 | return &folio_wait_table[hash_ptr(folio, PAGE_WAIT_TABLE_BITS)];
|
| 1036 | }
|
| 1037 |
|
| 1038 | void __init pagecache_init(void)
|
| 1039 | {
|
| 1040 | int i;
|
| 1041 |
|
| 1042 | for (i = 0; i < PAGE_WAIT_TABLE_SIZE; i++)
|
| 1043 | init_waitqueue_head(&folio_wait_table[i]);
|
| 1044 |
|
| 1045 | page_writeback_init();
|
| 1046 | }
|
| 1047 |
|
| 1048 | |
| 1049 | * The page wait code treats the "wait->flags" somewhat unusually, because
|
| 1050 | * we have multiple different kinds of waits, not just the usual "exclusive"
|
| 1051 | * one.
|
| 1052 | *
|
| 1053 | * We have:
|
| 1054 | *
|
| 1055 | * (a) no special bits set:
|
| 1056 | *
|
| 1057 | * We're just waiting for the bit to be released, and when a waker
|
| 1058 | * calls the wakeup function, we set WQ_FLAG_WOKEN and wake it up,
|
| 1059 | * and remove it from the wait queue.
|
| 1060 | *
|
| 1061 | * Simple and straightforward.
|
| 1062 | *
|
| 1063 | * (b) WQ_FLAG_EXCLUSIVE:
|
| 1064 | *
|
| 1065 | * The waiter is waiting to get the lock, and only one waiter should
|
| 1066 | * be woken up to avoid any thundering herd behavior. We'll set the
|
| 1067 | * WQ_FLAG_WOKEN bit, wake it up, and remove it from the wait queue.
|
| 1068 | *
|
| 1069 | * This is the traditional exclusive wait.
|
| 1070 | *
|
| 1071 | * (c) WQ_FLAG_EXCLUSIVE | WQ_FLAG_CUSTOM:
|
| 1072 | *
|
| 1073 | * The waiter is waiting to get the bit, and additionally wants the
|
| 1074 | * lock to be transferred to it for fair lock behavior. If the lock
|
| 1075 | * cannot be taken, we stop walking the wait queue without waking
|
| 1076 | * the waiter.
|
| 1077 | *
|
| 1078 | * This is the "fair lock handoff" case, and in addition to setting
|
| 1079 | * WQ_FLAG_WOKEN, we set WQ_FLAG_DONE to let the waiter easily see
|
| 1080 | * that it now has the lock.
|
| 1081 |
|
| 1082 | static int wake_page_function(wait_queue_entry_t *wait, unsigned mode, int sync, void *arg)
|
| 1083 | {
|
| 1084 | unsigned int flags;
|
| 1085 | struct wait_page_key *key = arg;
|
| 1086 | struct wait_page_queue *wait_page
|
| 1087 | = container_of(wait, struct wait_page_queue, wait);
|
| 1088 |
|
| 1089 | if (!wake_page_match(wait_page, key))
|
| 1090 | return 0;
|
| 1091 |
|
| 1092 | |
| 1093 | * If it's a lock handoff wait, we get the bit for it, and
|
| 1094 | * stop walking (and do not wake it up) if we can't.
|
| 1095 |
|
| 1096 | flags = wait->flags;
|
| 1097 | if (flags & WQ_FLAG_EXCLUSIVE) {
|
| 1098 | if (test_bit(key->bit_nr, &key->folio->flags))
|
| 1099 | return -1;
|
| 1100 | if (flags & WQ_FLAG_CUSTOM) {
|
| 1101 | if (test_and_set_bit(key->bit_nr, &key->folio->flags))
|
| 1102 | return -1;
|
| 1103 | flags |= WQ_FLAG_DONE;
|
| 1104 | }
|
| 1105 | }
|
| 1106 |
|
| 1107 | |
| 1108 | * We are holding the wait-queue lock, but the waiter that
|
| 1109 | * is waiting for this will be checking the flags without
|
| 1110 | * any locking.
|
| 1111 | *
|
| 1112 | * So update the flags atomically, and wake up the waiter
|
| 1113 | * afterwards to avoid any races. This store-release pairs
|
| 1114 | * with the load-acquire in folio_wait_bit_common().
|
| 1115 |
|
| 1116 | smp_store_release(&wait->flags, flags | WQ_FLAG_WOKEN);
|
| 1117 | wake_up_state(wait->private, mode);
|
| 1118 |
|
| 1119 | |
| 1120 | * Ok, we have successfully done what we're waiting for,
|
| 1121 | * and we can unconditionally remove the wait entry.
|
| 1122 | *
|
| 1123 | * Note that this pairs with the "finish_wait()" in the
|
| 1124 | * waiter, and has to be the absolute last thing we do.
|
| 1125 | * After this list_del_init(&wait->entry) the wait entry
|
| 1126 | * might be de-allocated and the process might even have
|
| 1127 | * exited.
|
| 1128 |
|
| 1129 | list_del_init_careful(&wait->entry);
|
| 1130 | return (flags & WQ_FLAG_EXCLUSIVE) != 0;
|
| 1131 | }
|
| 1132 |
|
| 1133 | static void folio_wake_bit(struct folio *folio, int bit_nr)
|
| 1134 | {
|
| 1135 | wait_queue_head_t *q = folio_waitqueue(folio);
|
| 1136 | struct wait_page_key key;
|
| 1137 | unsigned long flags;
|
| 1138 | wait_queue_entry_t bookmark;
|
| 1139 |
|
| 1140 | key.folio = folio;
|
| 1141 | key.bit_nr = bit_nr;
|
| 1142 | key.page_match = 0;
|
| 1143 |
|
| 1144 | bookmark.flags = 0;
|
| 1145 | bookmark.private = NULL;
|
| 1146 | bookmark.func = NULL;
|
| 1147 | INIT_LIST_HEAD(&bookmark.entry);
|
| 1148 |
|
| 1149 | spin_lock_irqsave(&q->lock, flags);
|
| 1150 | __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
|
| 1151 |
|
| 1152 | while (bookmark.flags & WQ_FLAG_BOOKMARK) {
|
| 1153 | |
| 1154 | * Take a breather from holding the lock,
|
| 1155 | * allow pages that finish wake up asynchronously
|
| 1156 | * to acquire the lock and remove themselves
|
| 1157 | * from wait queue
|
| 1158 |
|
| 1159 | spin_unlock_irqrestore(&q->lock, flags);
|
| 1160 | cpu_relax();
|
| 1161 | spin_lock_irqsave(&q->lock, flags);
|
| 1162 | __wake_up_locked_key_bookmark(q, TASK_NORMAL, &key, &bookmark);
|
| 1163 | }
|
| 1164 |
|
| 1165 | |
| 1166 | * It's possible to miss clearing waiters here, when we woke our page
|
| 1167 | * waiters, but the hashed waitqueue has waiters for other pages on it.
|
| 1168 | * That's okay, it's a rare case. The next waker will clear it.
|
| 1169 | *
|
| 1170 | * Note that, depending on the page pool (buddy, hugetlb, ZONE_DEVICE,
|
| 1171 | * other), the flag may be cleared in the course of freeing the page;
|
| 1172 | * but that is not required for correctness.
|
| 1173 |
|
| 1174 | if (!waitqueue_active(q) || !key.page_match)
|
| 1175 | folio_clear_waiters(folio);
|
| 1176 |
|
| 1177 | spin_unlock_irqrestore(&q->lock, flags);
|
| 1178 | }
|
| 1179 |
|
| 1180 | static void folio_wake(struct folio *folio, int bit)
|
| 1181 | {
|
| 1182 | if (!folio_test_waiters(folio))
|
| 1183 | return;
|
| 1184 | folio_wake_bit(folio, bit);
|
| 1185 | }
|
| 1186 |
|
| 1187 | |
| 1188 | * A choice of three behaviors for folio_wait_bit_common():
|
| 1189 |
|
| 1190 | enum behavior {
|
| 1191 | EXCLUSIVE, |
| 1192 | * __folio_lock() waiting on then setting PG_locked.
|
| 1193 |
|
| 1194 | SHARED, |
| 1195 | * folio_wait_writeback() waiting on PG_writeback.
|
| 1196 |
|
| 1197 | DROP, |
| 1198 | * like folio_put_wait_locked() on PG_locked.
|
| 1199 |
|
| 1200 | };
|
| 1201 |
|
| 1202 | |
| 1203 | * Attempt to check (or get) the folio flag, and mark us done
|
| 1204 | * if successful.
|
| 1205 |
|
| 1206 | static inline bool folio_trylock_flag(struct folio *folio, int bit_nr,
|
| 1207 | struct wait_queue_entry *wait)
|
| 1208 | {
|
| 1209 | if (wait->flags & WQ_FLAG_EXCLUSIVE) {
|
| 1210 | if (test_and_set_bit(bit_nr, &folio->flags))
|
| 1211 | return false;
|
| 1212 | } else if (test_bit(bit_nr, &folio->flags))
|
| 1213 | return false;
|
| 1214 |
|
| 1215 | wait->flags |= WQ_FLAG_WOKEN | WQ_FLAG_DONE;
|
| 1216 | return true;
|
| 1217 | }
|
| 1218 |
|
| 1219 |
|
| 1220 | int sysctl_page_lock_unfairness = 5;
|
| 1221 |
|
| 1222 | static inline int folio_wait_bit_common(struct folio *folio, int bit_nr,
|
| 1223 | int state, enum behavior behavior)
|
| 1224 | {
|
| 1225 | wait_queue_head_t *q = folio_waitqueue(folio);
|
| 1226 | int unfairness = sysctl_page_lock_unfairness;
|
| 1227 | struct wait_page_queue wait_page;
|
| 1228 | wait_queue_entry_t *wait = &wait_page.wait;
|
| 1229 | bool thrashing = false;
|
| 1230 | unsigned long pflags;
|
| 1231 | bool in_thrashing;
|
| 1232 |
|
| 1233 | if (bit_nr == PG_locked &&
|
| 1234 | !folio_test_uptodate(folio) && folio_test_workingset(folio)) {
|
| 1235 | delayacct_thrashing_start(&in_thrashing);
|
| 1236 | psi_memstall_enter(&pflags);
|
| 1237 | thrashing = true;
|
| 1238 | }
|
| 1239 |
|
| 1240 | init_wait(wait);
|
| 1241 | wait->func = wake_page_function;
|
| 1242 | wait_page.folio = folio;
|
| 1243 | wait_page.bit_nr = bit_nr;
|
| 1244 |
|
| 1245 | repeat:
|
| 1246 | wait->flags = 0;
|
| 1247 | if (behavior == EXCLUSIVE) {
|
| 1248 | wait->flags = WQ_FLAG_EXCLUSIVE;
|
| 1249 | if (--unfairness < 0)
|
| 1250 | wait->flags |= WQ_FLAG_CUSTOM;
|
| 1251 | }
|
| 1252 |
|
| 1253 | |
| 1254 | * Do one last check whether we can get the
|
| 1255 | * page bit synchronously.
|
| 1256 | *
|
| 1257 | * Do the folio_set_waiters() marking before that
|
| 1258 | * to let any waker we _just_ missed know they
|
| 1259 | * need to wake us up (otherwise they'll never
|
| 1260 | * even go to the slow case that looks at the
|
| 1261 | * page queue), and add ourselves to the wait
|
| 1262 | * queue if we need to sleep.
|
| 1263 | *
|
| 1264 | * This part needs to be done under the queue
|
| 1265 | * lock to avoid races.
|
| 1266 |
|
| 1267 | spin_lock_irq(&q->lock);
|
| 1268 | folio_set_waiters(folio);
|
| 1269 | if (!folio_trylock_flag(folio, bit_nr, wait))
|
| 1270 | __add_wait_queue_entry_tail(q, wait);
|
| 1271 | spin_unlock_irq(&q->lock);
|
| 1272 |
|
| 1273 | |
| 1274 | * From now on, all the logic will be based on
|
| 1275 | * the WQ_FLAG_WOKEN and WQ_FLAG_DONE flag, to
|
| 1276 | * see whether the page bit testing has already
|
| 1277 | * been done by the wake function.
|
| 1278 | *
|
| 1279 | * We can drop our reference to the folio.
|
| 1280 |
|
| 1281 | if (behavior == DROP)
|
| 1282 | folio_put(folio);
|
| 1283 |
|
| 1284 | |
| 1285 | * Note that until the "finish_wait()", or until
|
| 1286 | * we see the WQ_FLAG_WOKEN flag, we need to
|
| 1287 | * be very careful with the 'wait->flags', because
|
| 1288 | * we may race with a waker that sets them.
|
| 1289 |
|
| 1290 | for (;;) {
|
| 1291 | unsigned int flags;
|
| 1292 |
|
| 1293 | set_current_state(state);
|
| 1294 |
|
| 1295 |
|
| 1296 | flags = smp_load_acquire(&wait->flags);
|
| 1297 | if (!(flags & WQ_FLAG_WOKEN)) {
|
| 1298 | if (signal_pending_state(state, current))
|
| 1299 | break;
|
| 1300 |
|
| 1301 | io_schedule();
|
| 1302 | continue;
|
| 1303 | }
|
| 1304 |
|
| 1305 |
|
| 1306 | if (behavior != EXCLUSIVE)
|
| 1307 | break;
|
| 1308 |
|
| 1309 |
|
| 1310 | if (flags & WQ_FLAG_DONE)
|
| 1311 | break;
|
| 1312 |
|
| 1313 | |
| 1314 | * Otherwise, if we're getting the lock, we need to
|
| 1315 | * try to get it ourselves.
|
| 1316 | *
|
| 1317 | * And if that fails, we'll have to retry this all.
|
| 1318 |
|
| 1319 | if (unlikely(test_and_set_bit(bit_nr, folio_flags(folio, 0))))
|
| 1320 | goto repeat;
|
| 1321 |
|
| 1322 | wait->flags |= WQ_FLAG_DONE;
|
| 1323 | break;
|
| 1324 | }
|
| 1325 |
|
| 1326 | |
| 1327 | * If a signal happened, this 'finish_wait()' may remove the last
|
| 1328 | * waiter from the wait-queues, but the folio waiters bit will remain
|
| 1329 | * set. That's ok. The next wakeup will take care of it, and trying
|
| 1330 | * to do it here would be difficult and prone to races.
|
| 1331 |
|
| 1332 | finish_wait(q, wait);
|
| 1333 |
|
| 1334 | if (thrashing) {
|
| 1335 | delayacct_thrashing_end(&in_thrashing);
|
| 1336 | psi_memstall_leave(&pflags);
|
| 1337 | }
|
| 1338 |
|
| 1339 | |
| 1340 | * NOTE! The wait->flags weren't stable until we've done the
|
| 1341 | * 'finish_wait()', and we could have exited the loop above due
|
| 1342 | * to a signal, and had a wakeup event happen after the signal
|
| 1343 | * test but before the 'finish_wait()'.
|
| 1344 | *
|
| 1345 | * So only after the finish_wait() can we reliably determine
|
| 1346 | * if we got woken up or not, so we can now figure out the final
|
| 1347 | * return value based on that state without races.
|
| 1348 | *
|
| 1349 | * Also note that WQ_FLAG_WOKEN is sufficient for a non-exclusive
|
| 1350 | * waiter, but an exclusive one requires WQ_FLAG_DONE.
|
| 1351 |
|
| 1352 | if (behavior == EXCLUSIVE)
|
| 1353 | return wait->flags & WQ_FLAG_DONE ? 0 : -EINTR;
|
| 1354 |
|
| 1355 | return wait->flags & WQ_FLAG_WOKEN ? 0 : -EINTR;
|
| 1356 | }
|
| 1357 |
|
| 1358 | #ifdef CONFIG_MIGRATION
|
| 1359 | |
| 1360 | * migration_entry_wait_on_locked - Wait for a migration entry to be removed
|
| 1361 | * @entry: migration swap entry.
|
| 1362 | * @ptep: mapped pte pointer. Will return with the ptep unmapped. Only required
|
| 1363 | * for pte entries, pass NULL for pmd entries.
|
| 1364 | * @ptl: already locked ptl. This function will drop the lock.
|
| 1365 | *
|
| 1366 | * Wait for a migration entry referencing the given page to be removed. This is
|
| 1367 | * equivalent to put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE) except
|
| 1368 | * this can be called without taking a reference on the page. Instead this
|
| 1369 | * should be called while holding the ptl for the migration entry referencing
|
| 1370 | * the page.
|
| 1371 | *
|
| 1372 | * Returns after unmapping and unlocking the pte/ptl with pte_unmap_unlock().
|
| 1373 | *
|
| 1374 | * This follows the same logic as folio_wait_bit_common() so see the comments
|
| 1375 | * there.
|
| 1376 |
|
| 1377 | void migration_entry_wait_on_locked(swp_entry_t entry, pte_t *ptep,
|
| 1378 | spinlock_t *ptl)
|
| 1379 | {
|
| 1380 | struct wait_page_queue wait_page;
|
| 1381 | wait_queue_entry_t *wait = &wait_page.wait;
|
| 1382 | bool thrashing = false;
|
| 1383 | unsigned long pflags;
|
| 1384 | bool in_thrashing;
|
| 1385 | wait_queue_head_t *q;
|
| 1386 | struct folio *folio = page_folio(pfn_swap_entry_to_page(entry));
|
| 1387 |
|
| 1388 | q = folio_waitqueue(folio);
|
| 1389 | if (!folio_test_uptodate(folio) && folio_test_workingset(folio)) {
|
| 1390 | delayacct_thrashing_start(&in_thrashing);
|
| 1391 | psi_memstall_enter(&pflags);
|
| 1392 | thrashing = true;
|
| 1393 | }
|
| 1394 |
|
| 1395 | init_wait(wait);
|
| 1396 | wait->func = wake_page_function;
|
| 1397 | wait_page.folio = folio;
|
| 1398 | wait_page.bit_nr = PG_locked;
|
| 1399 | wait->flags = 0;
|
| 1400 |
|
| 1401 | spin_lock_irq(&q->lock);
|
| 1402 | folio_set_waiters(folio);
|
| 1403 | if (!folio_trylock_flag(folio, PG_locked, wait))
|
| 1404 | __add_wait_queue_entry_tail(q, wait);
|
| 1405 | spin_unlock_irq(&q->lock);
|
| 1406 |
|
| 1407 | |
| 1408 | * If a migration entry exists for the page the migration path must hold
|
| 1409 | * a valid reference to the page, and it must take the ptl to remove the
|
| 1410 | * migration entry. So the page is valid until the ptl is dropped.
|
| 1411 |
|
| 1412 | if (ptep)
|
| 1413 | pte_unmap_unlock(ptep, ptl);
|
| 1414 | else
|
| 1415 | spin_unlock(ptl);
|
| 1416 |
|
| 1417 | for (;;) {
|
| 1418 | unsigned int flags;
|
| 1419 |
|
| 1420 | set_current_state(TASK_UNINTERRUPTIBLE);
|
| 1421 |
|
| 1422 |
|
| 1423 | flags = smp_load_acquire(&wait->flags);
|
| 1424 | if (!(flags & WQ_FLAG_WOKEN)) {
|
| 1425 | if (signal_pending_state(TASK_UNINTERRUPTIBLE, current))
|
| 1426 | break;
|
| 1427 |
|
| 1428 | io_schedule();
|
| 1429 | continue;
|
| 1430 | }
|
| 1431 | break;
|
| 1432 | }
|
| 1433 |
|
| 1434 | finish_wait(q, wait);
|
| 1435 |
|
| 1436 | if (thrashing) {
|
| 1437 | delayacct_thrashing_end(&in_thrashing);
|
| 1438 | psi_memstall_leave(&pflags);
|
| 1439 | }
|
| 1440 | }
|
| 1441 | #endif
|
| 1442 |
|
| 1443 | void folio_wait_bit(struct folio *folio, int bit_nr)
|
| 1444 | {
|
| 1445 | folio_wait_bit_common(folio, bit_nr, TASK_UNINTERRUPTIBLE, SHARED);
|
| 1446 | }
|
| 1447 | EXPORT_SYMBOL(folio_wait_bit);
|
| 1448 |
|
| 1449 | int folio_wait_bit_killable(struct folio *folio, int bit_nr)
|
| 1450 | {
|
| 1451 | return folio_wait_bit_common(folio, bit_nr, TASK_KILLABLE, SHARED);
|
| 1452 | }
|
| 1453 | EXPORT_SYMBOL(folio_wait_bit_killable);
|
| 1454 |
|
| 1455 | |
| 1456 | * folio_put_wait_locked - Drop a reference and wait for it to be unlocked
|
| 1457 | * @folio: The folio to wait for.
|
| 1458 | * @state: The sleep state (TASK_KILLABLE, TASK_UNINTERRUPTIBLE, etc).
|
| 1459 | *
|
| 1460 | * The caller should hold a reference on @folio. They expect the page to
|
| 1461 | * become unlocked relatively soon, but do not wish to hold up migration
|
| 1462 | * (for example) by holding the reference while waiting for the folio to
|
| 1463 | * come unlocked. After this function returns, the caller should not
|
| 1464 | * dereference @folio.
|
| 1465 | *
|
| 1466 | * Return: 0 if the folio was unlocked or -EINTR if interrupted by a signal.
|
| 1467 |
|
| 1468 | static int folio_put_wait_locked(struct folio *folio, int state)
|
| 1469 | {
|
| 1470 | return folio_wait_bit_common(folio, PG_locked, state, DROP);
|
| 1471 | }
|
| 1472 |
|
| 1473 | |
| 1474 | * folio_add_wait_queue - Add an arbitrary waiter to a folio's wait queue
|
| 1475 | * @folio: Folio defining the wait queue of interest
|
| 1476 | * @waiter: Waiter to add to the queue
|
| 1477 | *
|
| 1478 | * Add an arbitrary @waiter to the wait queue for the nominated @folio.
|
| 1479 |
|
| 1480 | void folio_add_wait_queue(struct folio *folio, wait_queue_entry_t *waiter)
|
| 1481 | {
|
| 1482 | wait_queue_head_t *q = folio_waitqueue(folio);
|
| 1483 | unsigned long flags;
|
| 1484 |
|
| 1485 | spin_lock_irqsave(&q->lock, flags);
|
| 1486 | __add_wait_queue_entry_tail(q, waiter);
|
| 1487 | folio_set_waiters(folio);
|
| 1488 | spin_unlock_irqrestore(&q->lock, flags);
|
| 1489 | }
|
| 1490 | EXPORT_SYMBOL_GPL(folio_add_wait_queue);
|
| 1491 |
|
| 1492 | #ifndef clear_bit_unlock_is_negative_byte
|
| 1493 |
|
| 1494 | |
| 1495 | * PG_waiters is the high bit in the same byte as PG_lock.
|
| 1496 | *
|
| 1497 | * On x86 (and on many other architectures), we can clear PG_lock and
|
| 1498 | * test the sign bit at the same time. But if the architecture does
|
| 1499 | * not support that special operation, we just do this all by hand
|
| 1500 | * instead.
|
| 1501 | *
|
| 1502 | * The read of PG_waiters has to be after (or concurrently with) PG_locked
|
| 1503 | * being cleared, but a memory barrier should be unnecessary since it is
|
| 1504 | * in the same byte as PG_locked.
|
| 1505 |
|
| 1506 | static inline bool clear_bit_unlock_is_negative_byte(long nr, volatile void *mem)
|
| 1507 | {
|
| 1508 | clear_bit_unlock(nr, mem);
|
| 1509 |
|
| 1510 | return test_bit(PG_waiters, mem);
|
| 1511 | }
|
| 1512 |
|
| 1513 | #endif
|
| 1514 |
|
| 1515 | |
| 1516 | * folio_unlock - Unlock a locked folio.
|
| 1517 | * @folio: The folio.
|
| 1518 | *
|
| 1519 | * Unlocks the folio and wakes up any thread sleeping on the page lock.
|
| 1520 | *
|
| 1521 | * Context: May be called from interrupt or process context. May not be
|
| 1522 | * called from NMI context.
|
| 1523 |
|
| 1524 | void folio_unlock(struct folio *folio)
|
| 1525 | {
|
| 1526 |
|
| 1527 | BUILD_BUG_ON(PG_waiters != 7);
|
| 1528 | BUILD_BUG_ON(PG_locked > 7);
|
| 1529 | VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
|
| 1530 | if (clear_bit_unlock_is_negative_byte(PG_locked, folio_flags(folio, 0)))
|
| 1531 | folio_wake_bit(folio, PG_locked);
|
| 1532 | }
|
| 1533 | EXPORT_SYMBOL(folio_unlock);
|
| 1534 |
|
| 1535 | |
| 1536 | * folio_end_private_2 - Clear PG_private_2 and wake any waiters.
|
| 1537 | * @folio: The folio.
|
| 1538 | *
|
| 1539 | * Clear the PG_private_2 bit on a folio and wake up any sleepers waiting for
|
| 1540 | * it. The folio reference held for PG_private_2 being set is released.
|
| 1541 | *
|
| 1542 | * This is, for example, used when a netfs folio is being written to a local
|
| 1543 | * disk cache, thereby allowing writes to the cache for the same folio to be
|
| 1544 | * serialised.
|
| 1545 |
|
| 1546 | void folio_end_private_2(struct folio *folio)
|
| 1547 | {
|
| 1548 | VM_BUG_ON_FOLIO(!folio_test_private_2(folio), folio);
|
| 1549 | clear_bit_unlock(PG_private_2, folio_flags(folio, 0));
|
| 1550 | folio_wake_bit(folio, PG_private_2);
|
| 1551 | folio_put(folio);
|
| 1552 | }
|
| 1553 | EXPORT_SYMBOL(folio_end_private_2);
|
| 1554 |
|
| 1555 | |
| 1556 | * folio_wait_private_2 - Wait for PG_private_2 to be cleared on a folio.
|
| 1557 | * @folio: The folio to wait on.
|
| 1558 | *
|
| 1559 | * Wait for PG_private_2 (aka PG_fscache) to be cleared on a folio.
|
| 1560 |
|
| 1561 | void folio_wait_private_2(struct folio *folio)
|
| 1562 | {
|
| 1563 | while (folio_test_private_2(folio))
|
| 1564 | folio_wait_bit(folio, PG_private_2);
|
| 1565 | }
|
| 1566 | EXPORT_SYMBOL(folio_wait_private_2);
|
| 1567 |
|
| 1568 | |
| 1569 | * folio_wait_private_2_killable - Wait for PG_private_2 to be cleared on a folio.
|
| 1570 | * @folio: The folio to wait on.
|
| 1571 | *
|
| 1572 | * Wait for PG_private_2 (aka PG_fscache) to be cleared on a folio or until a
|
| 1573 | * fatal signal is received by the calling task.
|
| 1574 | *
|
| 1575 | * Return:
|
| 1576 | * - 0 if successful.
|
| 1577 | * - -EINTR if a fatal signal was encountered.
|
| 1578 |
|
| 1579 | int folio_wait_private_2_killable(struct folio *folio)
|
| 1580 | {
|
| 1581 | int ret = 0;
|
| 1582 |
|
| 1583 | while (folio_test_private_2(folio)) {
|
| 1584 | ret = folio_wait_bit_killable(folio, PG_private_2);
|
| 1585 | if (ret < 0)
|
| 1586 | break;
|
| 1587 | }
|
| 1588 |
|
| 1589 | return ret;
|
| 1590 | }
|
| 1591 | EXPORT_SYMBOL(folio_wait_private_2_killable);
|
| 1592 |
|
| 1593 | |
| 1594 | * folio_end_writeback - End writeback against a folio.
|
| 1595 | * @folio: The folio.
|
| 1596 |
|
| 1597 | void folio_end_writeback(struct folio *folio)
|
| 1598 | {
|
| 1599 | |
| 1600 | * folio_test_clear_reclaim() could be used here but it is an
|
| 1601 | * atomic operation and overkill in this particular case. Failing
|
| 1602 | * to shuffle a folio marked for immediate reclaim is too mild
|
| 1603 | * a gain to justify taking an atomic operation penalty at the
|
| 1604 | * end of every folio writeback.
|
| 1605 |
|
| 1606 | if (folio_test_reclaim(folio)) {
|
| 1607 | folio_clear_reclaim(folio);
|
| 1608 | folio_rotate_reclaimable(folio);
|
| 1609 | }
|
| 1610 |
|
| 1611 | |
| 1612 | * Writeback does not hold a folio reference of its own, relying
|
| 1613 | * on truncation to wait for the clearing of PG_writeback.
|
| 1614 | * But here we must make sure that the folio is not freed and
|
| 1615 | * reused before the folio_wake().
|
| 1616 |
|
| 1617 | folio_get(folio);
|
| 1618 | if (!__folio_end_writeback(folio))
|
| 1619 | BUG();
|
| 1620 |
|
| 1621 | smp_mb__after_atomic();
|
| 1622 | folio_wake(folio, PG_writeback);
|
| 1623 | acct_reclaim_writeback(folio);
|
| 1624 | folio_put(folio);
|
| 1625 | }
|
| 1626 | EXPORT_SYMBOL(folio_end_writeback);
|
| 1627 |
|
| 1628 | |
| 1629 | * After completing I/O on a page, call this routine to update the page
|
| 1630 | * flags appropriately
|
| 1631 |
|
| 1632 | void page_endio(struct page *page, bool is_write, int err)
|
| 1633 | {
|
| 1634 | struct folio *folio = page_folio(page);
|
| 1635 |
|
| 1636 | if (!is_write) {
|
| 1637 | if (!err) {
|
| 1638 | folio_mark_uptodate(folio);
|
| 1639 | } else {
|
| 1640 | folio_clear_uptodate(folio);
|
| 1641 | folio_set_error(folio);
|
| 1642 | }
|
| 1643 | folio_unlock(folio);
|
| 1644 | } else {
|
| 1645 | if (err) {
|
| 1646 | struct address_space *mapping;
|
| 1647 |
|
| 1648 | folio_set_error(folio);
|
| 1649 | mapping = folio_mapping(folio);
|
| 1650 | if (mapping)
|
| 1651 | mapping_set_error(mapping, err);
|
| 1652 | }
|
| 1653 | folio_end_writeback(folio);
|
| 1654 | }
|
| 1655 | }
|
| 1656 | EXPORT_SYMBOL_GPL(page_endio);
|
| 1657 |
|
| 1658 | |
| 1659 | * __folio_lock - Get a lock on the folio, assuming we need to sleep to get it.
|
| 1660 | * @folio: The folio to lock
|
| 1661 |
|
| 1662 | void __folio_lock(struct folio *folio)
|
| 1663 | {
|
| 1664 | folio_wait_bit_common(folio, PG_locked, TASK_UNINTERRUPTIBLE,
|
| 1665 | EXCLUSIVE);
|
| 1666 | }
|
| 1667 | EXPORT_SYMBOL(__folio_lock);
|
| 1668 |
|
| 1669 | int __folio_lock_killable(struct folio *folio)
|
| 1670 | {
|
| 1671 | return folio_wait_bit_common(folio, PG_locked, TASK_KILLABLE,
|
| 1672 | EXCLUSIVE);
|
| 1673 | }
|
| 1674 | EXPORT_SYMBOL_GPL(__folio_lock_killable);
|
| 1675 |
|
| 1676 | static int __folio_lock_async(struct folio *folio, struct wait_page_queue *wait)
|
| 1677 | {
|
| 1678 | struct wait_queue_head *q = folio_waitqueue(folio);
|
| 1679 | int ret = 0;
|
| 1680 |
|
| 1681 | wait->folio = folio;
|
| 1682 | wait->bit_nr = PG_locked;
|
| 1683 |
|
| 1684 | spin_lock_irq(&q->lock);
|
| 1685 | __add_wait_queue_entry_tail(q, &wait->wait);
|
| 1686 | folio_set_waiters(folio);
|
| 1687 | ret = !folio_trylock(folio);
|
| 1688 | |
| 1689 | * If we were successful now, we know we're still on the
|
| 1690 | * waitqueue as we're still under the lock. This means it's
|
| 1691 | * safe to remove and return success, we know the callback
|
| 1692 | * isn't going to trigger.
|
| 1693 |
|
| 1694 | if (!ret)
|
| 1695 | __remove_wait_queue(q, &wait->wait);
|
| 1696 | else
|
| 1697 | ret = -EIOCBQUEUED;
|
| 1698 | spin_unlock_irq(&q->lock);
|
| 1699 | return ret;
|
| 1700 | }
|
| 1701 |
|
| 1702 | |
| 1703 | * Return values:
|
| 1704 | * true - folio is locked; mmap_lock is still held.
|
| 1705 | * false - folio is not locked.
|
| 1706 | * mmap_lock has been released (mmap_read_unlock(), unless flags had both
|
| 1707 | * FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in
|
| 1708 | * which case mmap_lock is still held.
|
| 1709 | *
|
| 1710 | * If neither ALLOW_RETRY nor KILLABLE are set, will always return true
|
| 1711 | * with the folio locked and the mmap_lock unperturbed.
|
| 1712 |
|
| 1713 | bool __folio_lock_or_retry(struct folio *folio, struct mm_struct *mm,
|
| 1714 | unsigned int flags)
|
| 1715 | {
|
| 1716 | if (fault_flag_allow_retry_first(flags)) {
|
| 1717 | |
| 1718 | * CAUTION! In this case, mmap_lock is not released
|
| 1719 | * even though return 0.
|
| 1720 |
|
| 1721 | if (flags & FAULT_FLAG_RETRY_NOWAIT)
|
| 1722 | return false;
|
| 1723 |
|
| 1724 | mmap_read_unlock(mm);
|
| 1725 | if (flags & FAULT_FLAG_KILLABLE)
|
| 1726 | folio_wait_locked_killable(folio);
|
| 1727 | else
|
| 1728 | folio_wait_locked(folio);
|
| 1729 | return false;
|
| 1730 | }
|
| 1731 | if (flags & FAULT_FLAG_KILLABLE) {
|
| 1732 | bool ret;
|
| 1733 |
|
| 1734 | ret = __folio_lock_killable(folio);
|
| 1735 | if (ret) {
|
| 1736 | mmap_read_unlock(mm);
|
| 1737 | return false;
|
| 1738 | }
|
| 1739 | } else {
|
| 1740 | __folio_lock(folio);
|
| 1741 | }
|
| 1742 |
|
| 1743 | return true;
|
| 1744 | }
|
| 1745 |
|
| 1746 | |
| 1747 | * page_cache_next_miss() - Find the next gap in the page cache.
|
| 1748 | * @mapping: Mapping.
|
| 1749 | * @index: Index.
|
| 1750 | * @max_scan: Maximum range to search.
|
| 1751 | *
|
| 1752 | * Search the range [index, min(index + max_scan - 1, ULONG_MAX)] for the
|
| 1753 | * gap with the lowest index.
|
| 1754 | *
|
| 1755 | * This function may be called under the rcu_read_lock. However, this will
|
| 1756 | * not atomically search a snapshot of the cache at a single point in time.
|
| 1757 | * For example, if a gap is created at index 5, then subsequently a gap is
|
| 1758 | * created at index 10, page_cache_next_miss covering both indices may
|
| 1759 | * return 10 if called under the rcu_read_lock.
|
| 1760 | *
|
| 1761 | * Return: The index of the gap if found, otherwise an index outside the
|
| 1762 | * range specified (in which case 'return - index >= max_scan' will be true).
|
| 1763 | * In the rare case of index wrap-around, 0 will be returned. 0 will also
|
| 1764 | * be returned if index == 0 and there is a gap at the index. We can not
|
| 1765 | * wrap-around if passed index == 0.
|
| 1766 |
|
| 1767 | pgoff_t page_cache_next_miss(struct address_space *mapping,
|
| 1768 | pgoff_t index, unsigned long max_scan)
|
| 1769 | {
|
| 1770 | XA_STATE(xas, &mapping->i_pages, index);
|
| 1771 |
|
| 1772 | while (max_scan--) {
|
| 1773 | void *entry = xas_next(&xas);
|
| 1774 | if (!entry || xa_is_value(entry))
|
| 1775 | return xas.xa_index;
|
| 1776 | if (xas.xa_index == 0 && index != 0)
|
| 1777 | return xas.xa_index;
|
| 1778 | }
|
| 1779 |
|
| 1780 |
|
| 1781 | return xas.xa_index + 1;
|
| 1782 | }
|
| 1783 | EXPORT_SYMBOL(page_cache_next_miss);
|
| 1784 |
|
| 1785 | |
| 1786 | * page_cache_prev_miss() - Find the previous gap in the page cache.
|
| 1787 | * @mapping: Mapping.
|
| 1788 | * @index: Index.
|
| 1789 | * @max_scan: Maximum range to search.
|
| 1790 | *
|
| 1791 | * Search the range [max(index - max_scan + 1, 0), index] for the
|
| 1792 | * gap with the highest index.
|
| 1793 | *
|
| 1794 | * This function may be called under the rcu_read_lock. However, this will
|
| 1795 | * not atomically search a snapshot of the cache at a single point in time.
|
| 1796 | * For example, if a gap is created at index 10, then subsequently a gap is
|
| 1797 | * created at index 5, page_cache_prev_miss() covering both indices may
|
| 1798 | * return 5 if called under the rcu_read_lock.
|
| 1799 | *
|
| 1800 | * Return: The index of the gap if found, otherwise an index outside the
|
| 1801 | * range specified (in which case 'index - return >= max_scan' will be true).
|
| 1802 | * In the rare case of wrap-around, ULONG_MAX will be returned. ULONG_MAX
|
| 1803 | * will also be returned if index == ULONG_MAX and there is a gap at the
|
| 1804 | * index. We can not wrap-around if passed index == ULONG_MAX.
|
| 1805 |
|
| 1806 | pgoff_t page_cache_prev_miss(struct address_space *mapping,
|
| 1807 | pgoff_t index, unsigned long max_scan)
|
| 1808 | {
|
| 1809 | XA_STATE(xas, &mapping->i_pages, index);
|
| 1810 |
|
| 1811 | while (max_scan--) {
|
| 1812 | void *entry = xas_prev(&xas);
|
| 1813 | if (!entry || xa_is_value(entry))
|
| 1814 | return xas.xa_index;
|
| 1815 | if (xas.xa_index == ULONG_MAX && index != ULONG_MAX)
|
| 1816 | return xas.xa_index;
|
| 1817 | }
|
| 1818 |
|
| 1819 |
|
| 1820 | return xas.xa_index - 1;
|
| 1821 | }
|
| 1822 | EXPORT_SYMBOL(page_cache_prev_miss);
|
| 1823 |
|
| 1824 | |
| 1825 | * Lockless page cache protocol:
|
| 1826 | * On the lookup side:
|
| 1827 | * 1. Load the folio from i_pages
|
| 1828 | * 2. Increment the refcount if it's not zero
|
| 1829 | * 3. If the folio is not found by xas_reload(), put the refcount and retry
|
| 1830 | *
|
| 1831 | * On the removal side:
|
| 1832 | * A. Freeze the page (by zeroing the refcount if nobody else has a reference)
|
| 1833 | * B. Remove the page from i_pages
|
| 1834 | * C. Return the page to the page allocator
|
| 1835 | *
|
| 1836 | * This means that any page may have its reference count temporarily
|
| 1837 | * increased by a speculative page cache (or fast GUP) lookup as it can
|
| 1838 | * be allocated by another user before the RCU grace period expires.
|
| 1839 | * Because the refcount temporarily acquired here may end up being the
|
| 1840 | * last refcount on the page, any page allocation must be freeable by
|
| 1841 | * folio_put().
|
| 1842 |
|
| 1843 |
|
| 1844 | |
| 1845 | * filemap_get_entry - Get a page cache entry.
|
| 1846 | * @mapping: the address_space to search
|
| 1847 | * @index: The page cache index.
|
| 1848 | *
|
| 1849 | * Looks up the page cache entry at @mapping & @index. If it is a folio,
|
| 1850 | * it is returned with an increased refcount. If it is a shadow entry
|
| 1851 | * of a previously evicted folio, or a swap entry from shmem/tmpfs,
|
| 1852 | * it is returned without further action.
|
| 1853 | *
|
| 1854 | * Return: The folio, swap or shadow entry, %NULL if nothing is found.
|
| 1855 |
|
| 1856 | void *filemap_get_entry(struct address_space *mapping, pgoff_t index)
|
| 1857 | {
|
| 1858 | XA_STATE(xas, &mapping->i_pages, index);
|
| 1859 | struct folio *folio;
|
| 1860 |
|
| 1861 | rcu_read_lock();
|
| 1862 | repeat:
|
| 1863 | xas_reset(&xas);
|
| 1864 | folio = xas_load(&xas);
|
| 1865 | if (xas_retry(&xas, folio))
|
| 1866 | goto repeat;
|
| 1867 | |
| 1868 | * A shadow entry of a recently evicted page, or a swap entry from
|
| 1869 | * shmem/tmpfs. Return it without attempting to raise page count.
|
| 1870 |
|
| 1871 | if (!folio || xa_is_value(folio))
|
| 1872 | goto out;
|
| 1873 |
|
| 1874 | if (!folio_try_get_rcu(folio))
|
| 1875 | goto repeat;
|
| 1876 |
|
| 1877 | if (unlikely(folio != xas_reload(&xas))) {
|
| 1878 | folio_put(folio);
|
| 1879 | goto repeat;
|
| 1880 | }
|
| 1881 | out:
|
| 1882 | rcu_read_unlock();
|
| 1883 |
|
| 1884 | return folio;
|
| 1885 | }
|
| 1886 |
|
| 1887 | |
| 1888 | * __filemap_get_folio - Find and get a reference to a folio.
|
| 1889 | * @mapping: The address_space to search.
|
| 1890 | * @index: The page index.
|
| 1891 | * @fgp_flags: %FGP flags modify how the folio is returned.
|
| 1892 | * @gfp: Memory allocation flags to use if %FGP_CREAT is specified.
|
| 1893 | *
|
| 1894 | * Looks up the page cache entry at @mapping & @index.
|
| 1895 | *
|
| 1896 | * @fgp_flags can be zero or more of these flags:
|
| 1897 | *
|
| 1898 | * * %FGP_ACCESSED - The folio will be marked accessed.
|
| 1899 | * * %FGP_LOCK - The folio is returned locked.
|
| 1900 | * * %FGP_CREAT - If no page is present then a new page is allocated using
|
| 1901 | * @gfp and added to the page cache and the VM's LRU list.
|
| 1902 | * The page is returned locked and with an increased refcount.
|
| 1903 | * * %FGP_FOR_MMAP - The caller wants to do its own locking dance if the
|
| 1904 | * page is already in cache. If the page was allocated, unlock it before
|
| 1905 | * returning so the caller can do the same dance.
|
| 1906 | * * %FGP_WRITE - The page will be written to by the caller.
|
| 1907 | * * %FGP_NOFS - __GFP_FS will get cleared in gfp.
|
| 1908 | * * %FGP_NOWAIT - Don't get blocked by page lock.
|
| 1909 | * * %FGP_STABLE - Wait for the folio to be stable (finished writeback)
|
| 1910 | *
|
| 1911 | * If %FGP_LOCK or %FGP_CREAT are specified then the function may sleep even
|
| 1912 | * if the %GFP flags specified for %FGP_CREAT are atomic.
|
| 1913 | *
|
| 1914 | * If there is a page cache page, it is returned with an increased refcount.
|
| 1915 | *
|
| 1916 | * Return: The found folio or an ERR_PTR() otherwise.
|
| 1917 |
|
| 1918 | struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
|
| 1919 | int fgp_flags, gfp_t gfp)
|
| 1920 | {
|
| 1921 | struct folio *folio;
|
| 1922 |
|
| 1923 | repeat:
|
| 1924 | folio = filemap_get_entry(mapping, index);
|
| 1925 | if (xa_is_value(folio))
|
| 1926 | folio = NULL;
|
| 1927 | if (!folio)
|
| 1928 | goto no_page;
|
| 1929 |
|
| 1930 | if (fgp_flags & FGP_LOCK) {
|
| 1931 | if (fgp_flags & FGP_NOWAIT) {
|
| 1932 | if (!folio_trylock(folio)) {
|
| 1933 | folio_put(folio);
|
| 1934 | return ERR_PTR(-EAGAIN);
|
| 1935 | }
|
| 1936 | } else {
|
| 1937 | folio_lock(folio);
|
| 1938 | }
|
| 1939 |
|
| 1940 |
|
| 1941 | if (unlikely(folio->mapping != mapping)) {
|
| 1942 | folio_unlock(folio);
|
| 1943 | folio_put(folio);
|
| 1944 | goto repeat;
|
| 1945 | }
|
| 1946 | VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio);
|
| 1947 | }
|
| 1948 |
|
| 1949 | if (fgp_flags & FGP_ACCESSED)
|
| 1950 | folio_mark_accessed(folio);
|
| 1951 | else if (fgp_flags & FGP_WRITE) {
|
| 1952 |
|
| 1953 | if (folio_test_idle(folio))
|
| 1954 | folio_clear_idle(folio);
|
| 1955 | }
|
| 1956 |
|
| 1957 | if (fgp_flags & FGP_STABLE)
|
| 1958 | folio_wait_stable(folio);
|
| 1959 | no_page:
|
| 1960 | if (!folio && (fgp_flags & FGP_CREAT)) {
|
| 1961 | int err;
|
| 1962 | if ((fgp_flags & FGP_WRITE) && mapping_can_writeback(mapping))
|
| 1963 | gfp |= __GFP_WRITE;
|
| 1964 | if (fgp_flags & FGP_NOFS)
|
| 1965 | gfp &= ~__GFP_FS;
|
| 1966 | if (fgp_flags & FGP_NOWAIT) {
|
| 1967 | gfp &= ~GFP_KERNEL;
|
| 1968 | gfp |= GFP_NOWAIT | __GFP_NOWARN;
|
| 1969 | }
|
| 1970 |
|
| 1971 | folio = filemap_alloc_folio(gfp, 0);
|
| 1972 | if (!folio)
|
| 1973 | return ERR_PTR(-ENOMEM);
|
| 1974 |
|
| 1975 | if (WARN_ON_ONCE(!(fgp_flags & (FGP_LOCK | FGP_FOR_MMAP))))
|
| 1976 | fgp_flags |= FGP_LOCK;
|
| 1977 |
|
| 1978 |
|
| 1979 | if (fgp_flags & FGP_ACCESSED)
|
| 1980 | __folio_set_referenced(folio);
|
| 1981 |
|
| 1982 | err = filemap_add_folio(mapping, folio, index, gfp);
|
| 1983 | if (unlikely(err)) {
|
| 1984 | folio_put(folio);
|
| 1985 | folio = NULL;
|
| 1986 | if (err == -EEXIST)
|
| 1987 | goto repeat;
|
| 1988 | }
|
| 1989 |
|
| 1990 | |
| 1991 | * filemap_add_folio locks the page, and for mmap
|
| 1992 | * we expect an unlocked page.
|
| 1993 |
|
| 1994 | if (folio && (fgp_flags & FGP_FOR_MMAP))
|
| 1995 | folio_unlock(folio);
|
| 1996 | }
|
| 1997 |
|
| 1998 | if (!folio)
|
| 1999 | return ERR_PTR(-ENOENT);
|
| 2000 | return folio;
|
| 2001 | }
|
| 2002 | EXPORT_SYMBOL(__filemap_get_folio);
|
| 2003 |
|
| 2004 | static inline struct folio *find_get_entry(struct xa_state *xas, pgoff_t max,
|
| 2005 | xa_mark_t mark)
|
| 2006 | {
|
| 2007 | struct folio *folio;
|
| 2008 |
|
| 2009 | retry:
|
| 2010 | if (mark == XA_PRESENT)
|
| 2011 | folio = xas_find(xas, max);
|
| 2012 | else
|
| 2013 | folio = xas_find_marked(xas, max, mark);
|
| 2014 |
|
| 2015 | if (xas_retry(xas, folio))
|
| 2016 | goto retry;
|
| 2017 | |
| 2018 | * A shadow entry of a recently evicted page, a swap
|
| 2019 | * entry from shmem/tmpfs or a DAX entry. Return it
|
| 2020 | * without attempting to raise page count.
|
| 2021 |
|
| 2022 | if (!folio || xa_is_value(folio))
|
| 2023 | return folio;
|
| 2024 |
|
| 2025 | if (!folio_try_get_rcu(folio))
|
| 2026 | goto reset;
|
| 2027 |
|
| 2028 | if (unlikely(folio != xas_reload(xas))) {
|
| 2029 | folio_put(folio);
|
| 2030 | goto reset;
|
| 2031 | }
|
| 2032 |
|
| 2033 | return folio;
|
| 2034 | reset:
|
| 2035 | xas_reset(xas);
|
| 2036 | goto retry;
|
| 2037 | }
|
| 2038 |
|
| 2039 | |
| 2040 | * find_get_entries - gang pagecache lookup
|
| 2041 | * @mapping: The address_space to search
|
| 2042 | * @start: The starting page cache index
|
| 2043 | * @end: The final page index (inclusive).
|
| 2044 | * @fbatch: Where the resulting entries are placed.
|
| 2045 | * @indices: The cache indices corresponding to the entries in @entries
|
| 2046 | *
|
| 2047 | * find_get_entries() will search for and return a batch of entries in
|
| 2048 | * the mapping. The entries are placed in @fbatch. find_get_entries()
|
| 2049 | * takes a reference on any actual folios it returns.
|
| 2050 | *
|
| 2051 | * The entries have ascending indexes. The indices may not be consecutive
|
| 2052 | * due to not-present entries or large folios.
|
| 2053 | *
|
| 2054 | * Any shadow entries of evicted folios, or swap entries from
|
| 2055 | * shmem/tmpfs, are included in the returned array.
|
| 2056 | *
|
| 2057 | * Return: The number of entries which were found.
|
| 2058 |
|
| 2059 | unsigned find_get_entries(struct address_space *mapping, pgoff_t *start,
|
| 2060 | pgoff_t end, struct folio_batch *fbatch, pgoff_t *indices)
|
| 2061 | {
|
| 2062 | XA_STATE(xas, &mapping->i_pages, *start);
|
| 2063 | struct folio *folio;
|
| 2064 |
|
| 2065 | rcu_read_lock();
|
| 2066 | while ((folio = find_get_entry(&xas, end, XA_PRESENT)) != NULL) {
|
| 2067 | indices[fbatch->nr] = xas.xa_index;
|
| 2068 | if (!folio_batch_add(fbatch, folio))
|
| 2069 | break;
|
| 2070 | }
|
| 2071 | rcu_read_unlock();
|
| 2072 |
|
| 2073 | if (folio_batch_count(fbatch)) {
|
| 2074 | unsigned long nr = 1;
|
| 2075 | int idx = folio_batch_count(fbatch) - 1;
|
| 2076 |
|
| 2077 | folio = fbatch->folios[idx];
|
| 2078 | if (!xa_is_value(folio) && !folio_test_hugetlb(folio))
|
| 2079 | nr = folio_nr_pages(folio);
|
| 2080 | *start = indices[idx] + nr;
|
| 2081 | }
|
| 2082 | return folio_batch_count(fbatch);
|
| 2083 | }
|
| 2084 |
|
| 2085 | |
| 2086 | * find_lock_entries - Find a batch of pagecache entries.
|
| 2087 | * @mapping: The address_space to search.
|
| 2088 | * @start: The starting page cache index.
|
| 2089 | * @end: The final page index (inclusive).
|
| 2090 | * @fbatch: Where the resulting entries are placed.
|
| 2091 | * @indices: The cache indices of the entries in @fbatch.
|
| 2092 | *
|
| 2093 | * find_lock_entries() will return a batch of entries from @mapping.
|
| 2094 | * Swap, shadow and DAX entries are included. Folios are returned
|
| 2095 | * locked and with an incremented refcount. Folios which are locked
|
| 2096 | * by somebody else or under writeback are skipped. Folios which are
|
| 2097 | * partially outside the range are not returned.
|
| 2098 | *
|
| 2099 | * The entries have ascending indexes. The indices may not be consecutive
|
| 2100 | * due to not-present entries, large folios, folios which could not be
|
| 2101 | * locked or folios under writeback.
|
| 2102 | *
|
| 2103 | * Return: The number of entries which were found.
|
| 2104 |
|
| 2105 | unsigned find_lock_entries(struct address_space *mapping, pgoff_t *start,
|
| 2106 | pgoff_t end, struct folio_batch *fbatch, pgoff_t *indices)
|
| 2107 | {
|
| 2108 | XA_STATE(xas, &mapping->i_pages, *start);
|
| 2109 | struct folio *folio;
|
| 2110 |
|
| 2111 | rcu_read_lock();
|
| 2112 | while ((folio = find_get_entry(&xas, end, XA_PRESENT))) {
|
| 2113 | if (!xa_is_value(folio)) {
|
| 2114 | if (folio->index < *start)
|
| 2115 | goto put;
|
| 2116 | if (folio->index + folio_nr_pages(folio) - 1 > end)
|
| 2117 | goto put;
|
| 2118 | if (!folio_trylock(folio))
|
| 2119 | goto put;
|
| 2120 | if (folio->mapping != mapping ||
|
| 2121 | folio_test_writeback(folio))
|
| 2122 | goto unlock;
|
| 2123 | VM_BUG_ON_FOLIO(!folio_contains(folio, xas.xa_index),
|
| 2124 | folio);
|
| 2125 | }
|
| 2126 | indices[fbatch->nr] = xas.xa_index;
|
| 2127 | if (!folio_batch_add(fbatch, folio))
|
| 2128 | break;
|
| 2129 | continue;
|
| 2130 | unlock:
|
| 2131 | folio_unlock(folio);
|
| 2132 | put:
|
| 2133 | folio_put(folio);
|
| 2134 | }
|
| 2135 | rcu_read_unlock();
|
| 2136 |
|
| 2137 | if (folio_batch_count(fbatch)) {
|
| 2138 | unsigned long nr = 1;
|
| 2139 | int idx = folio_batch_count(fbatch) - 1;
|
| 2140 |
|
| 2141 | folio = fbatch->folios[idx];
|
| 2142 | if (!xa_is_value(folio) && !folio_test_hugetlb(folio))
|
| 2143 | nr = folio_nr_pages(folio);
|
| 2144 | *start = indices[idx] + nr;
|
| 2145 | }
|
| 2146 | return folio_batch_count(fbatch);
|
| 2147 | }
|
| 2148 |
|
| 2149 | |
| 2150 | * filemap_get_folios - Get a batch of folios
|
| 2151 | * @mapping: The address_space to search
|
| 2152 | * @start: The starting page index
|
| 2153 | * @end: The final page index (inclusive)
|
| 2154 | * @fbatch: The batch to fill.
|
| 2155 | *
|
| 2156 | * Search for and return a batch of folios in the mapping starting at
|
| 2157 | * index @start and up to index @end (inclusive). The folios are returned
|
| 2158 | * in @fbatch with an elevated reference count.
|
| 2159 | *
|
| 2160 | * The first folio may start before @start; if it does, it will contain
|
| 2161 | * @start. The final folio may extend beyond @end; if it does, it will
|
| 2162 | * contain @end. The folios have ascending indices. There may be gaps
|
| 2163 | * between the folios if there are indices which have no folio in the
|
| 2164 | * page cache. If folios are added to or removed from the page cache
|
| 2165 | * while this is running, they may or may not be found by this call.
|
| 2166 | *
|
| 2167 | * Return: The number of folios which were found.
|
| 2168 | * We also update @start to index the next folio for the traversal.
|
| 2169 |
|
| 2170 | unsigned filemap_get_folios(struct address_space *mapping, pgoff_t *start,
|
| 2171 | pgoff_t end, struct folio_batch *fbatch)
|
| 2172 | {
|
| 2173 | XA_STATE(xas, &mapping->i_pages, *start);
|
| 2174 | struct folio *folio;
|
| 2175 |
|
| 2176 | rcu_read_lock();
|
| 2177 | while ((folio = find_get_entry(&xas, end, XA_PRESENT)) != NULL) {
|
| 2178 |
|
| 2179 | if (xa_is_value(folio))
|
| 2180 | continue;
|
| 2181 | if (!folio_batch_add(fbatch, folio)) {
|
| 2182 | unsigned long nr = folio_nr_pages(folio);
|
| 2183 |
|
| 2184 | if (folio_test_hugetlb(folio))
|
| 2185 | nr = 1;
|
| 2186 | *start = folio->index + nr;
|
| 2187 | goto out;
|
| 2188 | }
|
| 2189 | }
|
| 2190 |
|
| 2191 | |
| 2192 | * We come here when there is no page beyond @end. We take care to not
|
| 2193 | * overflow the index @start as it confuses some of the callers. This
|
| 2194 | * breaks the iteration when there is a page at index -1 but that is
|
| 2195 | * already broken anyway.
|
| 2196 |
|
| 2197 | if (end == (pgoff_t)-1)
|
| 2198 | *start = (pgoff_t)-1;
|
| 2199 | else
|
| 2200 | *start = end + 1;
|
| 2201 | out:
|
| 2202 | rcu_read_unlock();
|
| 2203 |
|
| 2204 | return folio_batch_count(fbatch);
|
| 2205 | }
|
| 2206 | EXPORT_SYMBOL(filemap_get_folios);
|
| 2207 |
|
| 2208 | static inline
|
| 2209 | bool folio_more_pages(struct folio *folio, pgoff_t index, pgoff_t max)
|
| 2210 | {
|
| 2211 | if (!folio_test_large(folio) || folio_test_hugetlb(folio))
|
| 2212 | return false;
|
| 2213 | if (index >= max)
|
| 2214 | return false;
|
| 2215 | return index < folio->index + folio_nr_pages(folio) - 1;
|
| 2216 | }
|
| 2217 |
|
| 2218 | |
| 2219 | * filemap_get_folios_contig - Get a batch of contiguous folios
|
| 2220 | * @mapping: The address_space to search
|
| 2221 | * @start: The starting page index
|
| 2222 | * @end: The final page index (inclusive)
|
| 2223 | * @fbatch: The batch to fill
|
| 2224 | *
|
| 2225 | * filemap_get_folios_contig() works exactly like filemap_get_folios(),
|
| 2226 | * except the returned folios are guaranteed to be contiguous. This may
|
| 2227 | * not return all contiguous folios if the batch gets filled up.
|
| 2228 | *
|
| 2229 | * Return: The number of folios found.
|
| 2230 | * Also update @start to be positioned for traversal of the next folio.
|
| 2231 |
|
| 2232 |
|
| 2233 | unsigned filemap_get_folios_contig(struct address_space *mapping,
|
| 2234 | pgoff_t *start, pgoff_t end, struct folio_batch *fbatch)
|
| 2235 | {
|
| 2236 | XA_STATE(xas, &mapping->i_pages, *start);
|
| 2237 | unsigned long nr;
|
| 2238 | struct folio *folio;
|
| 2239 |
|
| 2240 | rcu_read_lock();
|
| 2241 |
|
| 2242 | for (folio = xas_load(&xas); folio && xas.xa_index <= end;
|
| 2243 | folio = xas_next(&xas)) {
|
| 2244 | if (xas_retry(&xas, folio))
|
| 2245 | continue;
|
| 2246 | |
| 2247 | * If the entry has been swapped out, we can stop looking.
|
| 2248 | * No current caller is looking for DAX entries.
|
| 2249 |
|
| 2250 | if (xa_is_value(folio))
|
| 2251 | goto update_start;
|
| 2252 |
|
| 2253 | if (!folio_try_get_rcu(folio))
|
| 2254 | goto retry;
|
| 2255 |
|
| 2256 | if (unlikely(folio != xas_reload(&xas)))
|
| 2257 | goto put_folio;
|
| 2258 |
|
| 2259 | if (!folio_batch_add(fbatch, folio)) {
|
| 2260 | nr = folio_nr_pages(folio);
|
| 2261 |
|
| 2262 | if (folio_test_hugetlb(folio))
|
| 2263 | nr = 1;
|
| 2264 | *start = folio->index + nr;
|
| 2265 | goto out;
|
| 2266 | }
|
| 2267 | continue;
|
| 2268 | put_folio:
|
| 2269 | folio_put(folio);
|
| 2270 |
|
| 2271 | retry:
|
| 2272 | xas_reset(&xas);
|
| 2273 | }
|
| 2274 |
|
| 2275 | update_start:
|
| 2276 | nr = folio_batch_count(fbatch);
|
| 2277 |
|
| 2278 | if (nr) {
|
| 2279 | folio = fbatch->folios[nr - 1];
|
| 2280 | if (folio_test_hugetlb(folio))
|
| 2281 | *start = folio->index + 1;
|
| 2282 | else
|
| 2283 | *start = folio->index + folio_nr_pages(folio);
|
| 2284 | }
|
| 2285 | out:
|
| 2286 | rcu_read_unlock();
|
| 2287 | return folio_batch_count(fbatch);
|
| 2288 | }
|
| 2289 | EXPORT_SYMBOL(filemap_get_folios_contig);
|
| 2290 |
|
| 2291 | |
| 2292 | * filemap_get_folios_tag - Get a batch of folios matching @tag
|
| 2293 | * @mapping: The address_space to search
|
| 2294 | * @start: The starting page index
|
| 2295 | * @end: The final page index (inclusive)
|
| 2296 | * @tag: The tag index
|
| 2297 | * @fbatch: The batch to fill
|
| 2298 | *
|
| 2299 | * Same as filemap_get_folios(), but only returning folios tagged with @tag.
|
| 2300 | *
|
| 2301 | * Return: The number of folios found.
|
| 2302 | * Also update @start to index the next folio for traversal.
|
| 2303 |
|
| 2304 | unsigned filemap_get_folios_tag(struct address_space *mapping, pgoff_t *start,
|
| 2305 | pgoff_t end, xa_mark_t tag, struct folio_batch *fbatch)
|
| 2306 | {
|
| 2307 | XA_STATE(xas, &mapping->i_pages, *start);
|
| 2308 | struct folio *folio;
|
| 2309 |
|
| 2310 | rcu_read_lock();
|
| 2311 | while ((folio = find_get_entry(&xas, end, tag)) != NULL) {
|
| 2312 | |
| 2313 | * Shadow entries should never be tagged, but this iteration
|
| 2314 | * is lockless so there is a window for page reclaim to evict
|
| 2315 | * a page we saw tagged. Skip over it.
|
| 2316 |
|
| 2317 | if (xa_is_value(folio))
|
| 2318 | continue;
|
| 2319 | if (!folio_batch_add(fbatch, folio)) {
|
| 2320 | unsigned long nr = folio_nr_pages(folio);
|
| 2321 |
|
| 2322 | if (folio_test_hugetlb(folio))
|
| 2323 | nr = 1;
|
| 2324 | *start = folio->index + nr;
|
| 2325 | goto out;
|
| 2326 | }
|
| 2327 | }
|
| 2328 | |
| 2329 | * We come here when there is no page beyond @end. We take care to not
|
| 2330 | * overflow the index @start as it confuses some of the callers. This
|
| 2331 | * breaks the iteration when there is a page at index -1 but that is
|
| 2332 | * already broke anyway.
|
| 2333 |
|
| 2334 | if (end == (pgoff_t)-1)
|
| 2335 | *start = (pgoff_t)-1;
|
| 2336 | else
|
| 2337 | *start = end + 1;
|
| 2338 | out:
|
| 2339 | rcu_read_unlock();
|
| 2340 |
|
| 2341 | return folio_batch_count(fbatch);
|
| 2342 | }
|
| 2343 | EXPORT_SYMBOL(filemap_get_folios_tag);
|
| 2344 |
|
| 2345 | |
| 2346 | * CD/DVDs are error prone. When a medium error occurs, the driver may fail
|
| 2347 | * a _large_ part of the i/o request. Imagine the worst scenario:
|
| 2348 | *
|
| 2349 | * ---R__________________________________________B__________
|
| 2350 | * ^ reading here ^ bad block(assume 4k)
|
| 2351 | *
|
| 2352 | * read(R) => miss => readahead(R...B) => media error => frustrating retries
|
| 2353 | * => failing the whole request => read(R) => read(R+1) =>
|
| 2354 | * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
|
| 2355 | * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
|
| 2356 | * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
|
| 2357 | *
|
| 2358 | * It is going insane. Fix it by quickly scaling down the readahead size.
|
| 2359 |
|
| 2360 | static void shrink_readahead_size_eio(struct file_ra_state *ra)
|
| 2361 | {
|
| 2362 | ra->ra_pages /= 4;
|
| 2363 | }
|
| 2364 |
|
| 2365 | |
| 2366 | * filemap_get_read_batch - Get a batch of folios for read
|
| 2367 | *
|
| 2368 | * Get a batch of folios which represent a contiguous range of bytes in
|
| 2369 | * the file. No exceptional entries will be returned. If @index is in
|
| 2370 | * the middle of a folio, the entire folio will be returned. The last
|
| 2371 | * folio in the batch may have the readahead flag set or the uptodate flag
|
| 2372 | * clear so that the caller can take the appropriate action.
|
| 2373 |
|
| 2374 | static void filemap_get_read_batch(struct address_space *mapping,
|
| 2375 | pgoff_t index, pgoff_t max, struct folio_batch *fbatch)
|
| 2376 | {
|
| 2377 | XA_STATE(xas, &mapping->i_pages, index);
|
| 2378 | struct folio *folio;
|
| 2379 |
|
| 2380 | rcu_read_lock();
|
| 2381 | for (folio = xas_load(&xas); folio; folio = xas_next(&xas)) {
|
| 2382 | if (xas_retry(&xas, folio))
|
| 2383 | continue;
|
| 2384 | if (xas.xa_index > max || xa_is_value(folio))
|
| 2385 | break;
|
| 2386 | if (xa_is_sibling(folio))
|
| 2387 | break;
|
| 2388 | if (!folio_try_get_rcu(folio))
|
| 2389 | goto retry;
|
| 2390 |
|
| 2391 | if (unlikely(folio != xas_reload(&xas)))
|
| 2392 | goto put_folio;
|
| 2393 |
|
| 2394 | if (!folio_batch_add(fbatch, folio))
|
| 2395 | break;
|
| 2396 | if (!folio_test_uptodate(folio))
|
| 2397 | break;
|
| 2398 | if (folio_test_readahead(folio))
|
| 2399 | break;
|
| 2400 | xas_advance(&xas, folio->index + folio_nr_pages(folio) - 1);
|
| 2401 | continue;
|
| 2402 | put_folio:
|
| 2403 | folio_put(folio);
|
| 2404 | retry:
|
| 2405 | xas_reset(&xas);
|
| 2406 | }
|
| 2407 | rcu_read_unlock();
|
| 2408 | }
|
| 2409 |
|
| 2410 | static int filemap_read_folio(struct file *file, filler_t filler,
|
| 2411 | struct folio *folio)
|
| 2412 | {
|
| 2413 | bool workingset = folio_test_workingset(folio);
|
| 2414 | unsigned long pflags;
|
| 2415 | int error;
|
| 2416 |
|
| 2417 | |
| 2418 | * A previous I/O error may have been due to temporary failures,
|
| 2419 | * eg. multipath errors. PG_error will be set again if read_folio
|
| 2420 | * fails.
|
| 2421 |
|
| 2422 | folio_clear_error(folio);
|
| 2423 |
|
| 2424 |
|
| 2425 | if (unlikely(workingset))
|
| 2426 | psi_memstall_enter(&pflags);
|
| 2427 | error = filler(file, folio);
|
| 2428 | if (unlikely(workingset))
|
| 2429 | psi_memstall_leave(&pflags);
|
| 2430 | if (error)
|
| 2431 | return error;
|
| 2432 |
|
| 2433 | error = folio_wait_locked_killable(folio);
|
| 2434 | if (error)
|
| 2435 | return error;
|
| 2436 | if (folio_test_uptodate(folio))
|
| 2437 | return 0;
|
| 2438 | if (file)
|
| 2439 | shrink_readahead_size_eio(&file->f_ra);
|
| 2440 | return -EIO;
|
| 2441 | }
|
| 2442 |
|
| 2443 | static bool filemap_range_uptodate(struct address_space *mapping,
|
| 2444 | loff_t pos, size_t count, struct folio *folio,
|
| 2445 | bool need_uptodate)
|
| 2446 | {
|
| 2447 | if (folio_test_uptodate(folio))
|
| 2448 | return true;
|
| 2449 |
|
| 2450 | if (need_uptodate)
|
| 2451 | return false;
|
| 2452 | if (!mapping->a_ops->is_partially_uptodate)
|
| 2453 | return false;
|
| 2454 | if (mapping->host->i_blkbits >= folio_shift(folio))
|
| 2455 | return false;
|
| 2456 |
|
| 2457 | if (folio_pos(folio) > pos) {
|
| 2458 | count -= folio_pos(folio) - pos;
|
| 2459 | pos = 0;
|
| 2460 | } else {
|
| 2461 | pos -= folio_pos(folio);
|
| 2462 | }
|
| 2463 |
|
| 2464 | return mapping->a_ops->is_partially_uptodate(folio, pos, count);
|
| 2465 | }
|
| 2466 |
|
| 2467 | static int filemap_update_page(struct kiocb *iocb,
|
| 2468 | struct address_space *mapping, size_t count,
|
| 2469 | struct folio *folio, bool need_uptodate)
|
| 2470 | {
|
| 2471 | int error;
|
| 2472 |
|
| 2473 | if (iocb->ki_flags & IOCB_NOWAIT) {
|
| 2474 | if (!filemap_invalidate_trylock_shared(mapping))
|
| 2475 | return -EAGAIN;
|
| 2476 | } else {
|
| 2477 | filemap_invalidate_lock_shared(mapping);
|
| 2478 | }
|
| 2479 |
|
| 2480 | if (!folio_trylock(folio)) {
|
| 2481 | error = -EAGAIN;
|
| 2482 | if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_NOIO))
|
| 2483 | goto unlock_mapping;
|
| 2484 | if (!(iocb->ki_flags & IOCB_WAITQ)) {
|
| 2485 | filemap_invalidate_unlock_shared(mapping);
|
| 2486 | |
| 2487 | * This is where we usually end up waiting for a
|
| 2488 | * previously submitted readahead to finish.
|
| 2489 |
|
| 2490 | folio_put_wait_locked(folio, TASK_KILLABLE);
|
| 2491 | return AOP_TRUNCATED_PAGE;
|
| 2492 | }
|
| 2493 | error = __folio_lock_async(folio, iocb->ki_waitq);
|
| 2494 | if (error)
|
| 2495 | goto unlock_mapping;
|
| 2496 | }
|
| 2497 |
|
| 2498 | error = AOP_TRUNCATED_PAGE;
|
| 2499 | if (!folio->mapping)
|
| 2500 | goto unlock;
|
| 2501 |
|
| 2502 | error = 0;
|
| 2503 | if (filemap_range_uptodate(mapping, iocb->ki_pos, count, folio,
|
| 2504 | need_uptodate))
|
| 2505 | goto unlock;
|
| 2506 |
|
| 2507 | error = -EAGAIN;
|
| 2508 | if (iocb->ki_flags & (IOCB_NOIO | IOCB_NOWAIT | IOCB_WAITQ))
|
| 2509 | goto unlock;
|
| 2510 |
|
| 2511 | error = filemap_read_folio(iocb->ki_filp, mapping->a_ops->read_folio,
|
| 2512 | folio);
|
| 2513 | goto unlock_mapping;
|
| 2514 | unlock:
|
| 2515 | folio_unlock(folio);
|
| 2516 | unlock_mapping:
|
| 2517 | filemap_invalidate_unlock_shared(mapping);
|
| 2518 | if (error == AOP_TRUNCATED_PAGE)
|
| 2519 | folio_put(folio);
|
| 2520 | return error;
|
| 2521 | }
|
| 2522 |
|
| 2523 | static int filemap_create_folio(struct file *file,
|
| 2524 | struct address_space *mapping, pgoff_t index,
|
| 2525 | struct folio_batch *fbatch)
|
| 2526 | {
|
| 2527 | struct folio *folio;
|
| 2528 | int error;
|
| 2529 |
|
| 2530 | folio = filemap_alloc_folio(mapping_gfp_mask(mapping), 0);
|
| 2531 | if (!folio)
|
| 2532 | return -ENOMEM;
|
| 2533 |
|
| 2534 | |
| 2535 | * Protect against truncate / hole punch. Grabbing invalidate_lock
|
| 2536 | * here assures we cannot instantiate and bring uptodate new
|
| 2537 | * pagecache folios after evicting page cache during truncate
|
| 2538 | * and before actually freeing blocks. Note that we could
|
| 2539 | * release invalidate_lock after inserting the folio into
|
| 2540 | * the page cache as the locked folio would then be enough to
|
| 2541 | * synchronize with hole punching. But there are code paths
|
| 2542 | * such as filemap_update_page() filling in partially uptodate
|
| 2543 | * pages or ->readahead() that need to hold invalidate_lock
|
| 2544 | * while mapping blocks for IO so let's hold the lock here as
|
| 2545 | * well to keep locking rules simple.
|
| 2546 |
|
| 2547 | filemap_invalidate_lock_shared(mapping);
|
| 2548 | error = filemap_add_folio(mapping, folio, index,
|
| 2549 | mapping_gfp_constraint(mapping, GFP_KERNEL));
|
| 2550 | if (error == -EEXIST)
|
| 2551 | error = AOP_TRUNCATED_PAGE;
|
| 2552 | if (error)
|
| 2553 | goto error;
|
| 2554 |
|
| 2555 | error = filemap_read_folio(file, mapping->a_ops->read_folio, folio);
|
| 2556 | if (error)
|
| 2557 | goto error;
|
| 2558 |
|
| 2559 | filemap_invalidate_unlock_shared(mapping);
|
| 2560 | folio_batch_add(fbatch, folio);
|
| 2561 | return 0;
|
| 2562 | error:
|
| 2563 | filemap_invalidate_unlock_shared(mapping);
|
| 2564 | folio_put(folio);
|
| 2565 | return error;
|
| 2566 | }
|
| 2567 |
|
| 2568 | static int filemap_readahead(struct kiocb *iocb, struct file *file,
|
| 2569 | struct address_space *mapping, struct folio *folio,
|
| 2570 | pgoff_t last_index)
|
| 2571 | {
|
| 2572 | DEFINE_READAHEAD(ractl, file, &file->f_ra, mapping, folio->index);
|
| 2573 |
|
| 2574 | if (iocb->ki_flags & IOCB_NOIO)
|
| 2575 | return -EAGAIN;
|
| 2576 | page_cache_async_ra(&ractl, folio, last_index - folio->index);
|
| 2577 | return 0;
|
| 2578 | }
|
| 2579 |
|
| 2580 | static int filemap_get_pages(struct kiocb *iocb, size_t count,
|
| 2581 | struct folio_batch *fbatch, bool need_uptodate)
|
| 2582 | {
|
| 2583 | struct file *filp = iocb->ki_filp;
|
| 2584 | struct address_space *mapping = filp->f_mapping;
|
| 2585 | struct file_ra_state *ra = &filp->f_ra;
|
| 2586 | pgoff_t index = iocb->ki_pos >> PAGE_SHIFT;
|
| 2587 | pgoff_t last_index;
|
| 2588 | struct folio *folio;
|
| 2589 | int err = 0;
|
| 2590 |
|
| 2591 |
|
| 2592 | last_index = DIV_ROUND_UP(iocb->ki_pos + count, PAGE_SIZE);
|
| 2593 | retry:
|
| 2594 | if (fatal_signal_pending(current))
|
| 2595 | return -EINTR;
|
| 2596 |
|
| 2597 | filemap_get_read_batch(mapping, index, last_index - 1, fbatch);
|
| 2598 | if (!folio_batch_count(fbatch)) {
|
| 2599 | if (iocb->ki_flags & IOCB_NOIO)
|
| 2600 | return -EAGAIN;
|
| 2601 | page_cache_sync_readahead(mapping, ra, filp, index,
|
| 2602 | last_index - index);
|
| 2603 | filemap_get_read_batch(mapping, index, last_index - 1, fbatch);
|
| 2604 | }
|
| 2605 | if (!folio_batch_count(fbatch)) {
|
| 2606 | if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
|
| 2607 | return -EAGAIN;
|
| 2608 | err = filemap_create_folio(filp, mapping,
|
| 2609 | iocb->ki_pos >> PAGE_SHIFT, fbatch);
|
| 2610 | if (err == AOP_TRUNCATED_PAGE)
|
| 2611 | goto retry;
|
| 2612 | return err;
|
| 2613 | }
|
| 2614 |
|
| 2615 | folio = fbatch->folios[folio_batch_count(fbatch) - 1];
|
| 2616 | if (folio_test_readahead(folio)) {
|
| 2617 | err = filemap_readahead(iocb, filp, mapping, folio, last_index);
|
| 2618 | if (err)
|
| 2619 | goto err;
|
| 2620 | }
|
| 2621 | if (!folio_test_uptodate(folio)) {
|
| 2622 | if ((iocb->ki_flags & IOCB_WAITQ) &&
|
| 2623 | folio_batch_count(fbatch) > 1)
|
| 2624 | iocb->ki_flags |= IOCB_NOWAIT;
|
| 2625 | err = filemap_update_page(iocb, mapping, count, folio,
|
| 2626 | need_uptodate);
|
| 2627 | if (err)
|
| 2628 | goto err;
|
| 2629 | }
|
| 2630 |
|
| 2631 | return 0;
|
| 2632 | err:
|
| 2633 | if (err < 0)
|
| 2634 | folio_put(folio);
|
| 2635 | if (likely(--fbatch->nr))
|
| 2636 | return 0;
|
| 2637 | if (err == AOP_TRUNCATED_PAGE)
|
| 2638 | goto retry;
|
| 2639 | return err;
|
| 2640 | }
|
| 2641 |
|
| 2642 | static inline bool pos_same_folio(loff_t pos1, loff_t pos2, struct folio *folio)
|
| 2643 | {
|
| 2644 | unsigned int shift = folio_shift(folio);
|
| 2645 |
|
| 2646 | return (pos1 >> shift == pos2 >> shift);
|
| 2647 | }
|
| 2648 |
|
| 2649 | |
| 2650 | * filemap_read - Read data from the page cache.
|
| 2651 | * @iocb: The iocb to read.
|
| 2652 | * @iter: Destination for the data.
|
| 2653 | * @already_read: Number of bytes already read by the caller.
|
| 2654 | *
|
| 2655 | * Copies data from the page cache. If the data is not currently present,
|
| 2656 | * uses the readahead and read_folio address_space operations to fetch it.
|
| 2657 | *
|
| 2658 | * Return: Total number of bytes copied, including those already read by
|
| 2659 | * the caller. If an error happens before any bytes are copied, returns
|
| 2660 | * a negative error number.
|
| 2661 |
|
| 2662 | ssize_t filemap_read(struct kiocb *iocb, struct iov_iter *iter,
|
| 2663 | ssize_t already_read)
|
| 2664 | {
|
| 2665 | struct file *filp = iocb->ki_filp;
|
| 2666 | struct file_ra_state *ra = &filp->f_ra;
|
| 2667 | struct address_space *mapping = filp->f_mapping;
|
| 2668 | struct inode *inode = mapping->host;
|
| 2669 | struct folio_batch fbatch;
|
| 2670 | int i, error = 0;
|
| 2671 | bool writably_mapped;
|
| 2672 | loff_t isize, end_offset;
|
| 2673 |
|
| 2674 | if (unlikely(iocb->ki_pos >= inode->i_sb->s_maxbytes))
|
| 2675 | return 0;
|
| 2676 | if (unlikely(!iov_iter_count(iter)))
|
| 2677 | return 0;
|
| 2678 |
|
| 2679 | iov_iter_truncate(iter, inode->i_sb->s_maxbytes);
|
| 2680 | folio_batch_init(&fbatch);
|
| 2681 |
|
| 2682 | do {
|
| 2683 | cond_resched();
|
| 2684 |
|
| 2685 | |
| 2686 | * If we've already successfully copied some data, then we
|
| 2687 | * can no longer safely return -EIOCBQUEUED. Hence mark
|
| 2688 | * an async read NOWAIT at that point.
|
| 2689 |
|
| 2690 | if ((iocb->ki_flags & IOCB_WAITQ) && already_read)
|
| 2691 | iocb->ki_flags |= IOCB_NOWAIT;
|
| 2692 |
|
| 2693 | if (unlikely(iocb->ki_pos >= i_size_read(inode)))
|
| 2694 | break;
|
| 2695 |
|
| 2696 | error = filemap_get_pages(iocb, iter->count, &fbatch,
|
| 2697 | iov_iter_is_pipe(iter));
|
| 2698 | if (error < 0)
|
| 2699 | break;
|
| 2700 |
|
| 2701 | |
| 2702 | * i_size must be checked after we know the pages are Uptodate.
|
| 2703 | *
|
| 2704 | * Checking i_size after the check allows us to calculate
|
| 2705 | * the correct value for "nr", which means the zero-filled
|
| 2706 | * part of the page is not copied back to userspace (unless
|
| 2707 | * another truncate extends the file - this is desired though).
|
| 2708 |
|
| 2709 | isize = i_size_read(inode);
|
| 2710 | if (unlikely(iocb->ki_pos >= isize))
|
| 2711 | goto put_folios;
|
| 2712 | end_offset = min_t(loff_t, isize, iocb->ki_pos + iter->count);
|
| 2713 |
|
| 2714 | |
| 2715 | * Once we start copying data, we don't want to be touching any
|
| 2716 | * cachelines that might be contended:
|
| 2717 |
|
| 2718 | writably_mapped = mapping_writably_mapped(mapping);
|
| 2719 |
|
| 2720 | |
| 2721 | * When a read accesses the same folio several times, only
|
| 2722 | * mark it as accessed the first time.
|
| 2723 |
|
| 2724 | if (!pos_same_folio(iocb->ki_pos, ra->prev_pos - 1,
|
| 2725 | fbatch.folios[0]))
|
| 2726 | folio_mark_accessed(fbatch.folios[0]);
|
| 2727 |
|
| 2728 | for (i = 0; i < folio_batch_count(&fbatch); i++) {
|
| 2729 | struct folio *folio = fbatch.folios[i];
|
| 2730 | size_t fsize = folio_size(folio);
|
| 2731 | size_t offset = iocb->ki_pos & (fsize - 1);
|
| 2732 | size_t bytes = min_t(loff_t, end_offset - iocb->ki_pos,
|
| 2733 | fsize - offset);
|
| 2734 | size_t copied;
|
| 2735 |
|
| 2736 | if (end_offset < folio_pos(folio))
|
| 2737 | break;
|
| 2738 | if (i > 0)
|
| 2739 | folio_mark_accessed(folio);
|
| 2740 | |
| 2741 | * If users can be writing to this folio using arbitrary
|
| 2742 | * virtual addresses, take care of potential aliasing
|
| 2743 | * before reading the folio on the kernel side.
|
| 2744 |
|
| 2745 | if (writably_mapped)
|
| 2746 | flush_dcache_folio(folio);
|
| 2747 |
|
| 2748 | copied = copy_folio_to_iter(folio, offset, bytes, iter);
|
| 2749 |
|
| 2750 | already_read += copied;
|
| 2751 | iocb->ki_pos += copied;
|
| 2752 | ra->prev_pos = iocb->ki_pos;
|
| 2753 |
|
| 2754 | if (copied < bytes) {
|
| 2755 | error = -EFAULT;
|
| 2756 | break;
|
| 2757 | }
|
| 2758 | }
|
| 2759 | put_folios:
|
| 2760 | for (i = 0; i < folio_batch_count(&fbatch); i++)
|
| 2761 | folio_put(fbatch.folios[i]);
|
| 2762 | folio_batch_init(&fbatch);
|
| 2763 | } while (iov_iter_count(iter) && iocb->ki_pos < isize && !error);
|
| 2764 |
|
| 2765 | file_accessed(filp);
|
| 2766 |
|
| 2767 | return already_read ? already_read : error;
|
| 2768 | }
|
| 2769 | EXPORT_SYMBOL_GPL(filemap_read);
|
| 2770 |
|
| 2771 | |
| 2772 | * generic_file_read_iter - generic filesystem read routine
|
| 2773 | * @iocb: kernel I/O control block
|
| 2774 | * @iter: destination for the data read
|
| 2775 | *
|
| 2776 | * This is the "read_iter()" routine for all filesystems
|
| 2777 | * that can use the page cache directly.
|
| 2778 | *
|
| 2779 | * The IOCB_NOWAIT flag in iocb->ki_flags indicates that -EAGAIN shall
|
| 2780 | * be returned when no data can be read without waiting for I/O requests
|
| 2781 | * to complete; it doesn't prevent readahead.
|
| 2782 | *
|
| 2783 | * The IOCB_NOIO flag in iocb->ki_flags indicates that no new I/O
|
| 2784 | * requests shall be made for the read or for readahead. When no data
|
| 2785 | * can be read, -EAGAIN shall be returned. When readahead would be
|
| 2786 | * triggered, a partial, possibly empty read shall be returned.
|
| 2787 | *
|
| 2788 | * Return:
|
| 2789 | * * number of bytes copied, even for partial reads
|
| 2790 | * * negative error code (or 0 if IOCB_NOIO) if nothing was read
|
| 2791 |
|
| 2792 | ssize_t
|
| 2793 | generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
|
| 2794 | {
|
| 2795 | size_t count = iov_iter_count(iter);
|
| 2796 | ssize_t retval = 0;
|
| 2797 |
|
| 2798 | if (!count)
|
| 2799 | return 0;
|
| 2800 |
|
| 2801 | if (iocb->ki_flags & IOCB_DIRECT) {
|
| 2802 | struct file *file = iocb->ki_filp;
|
| 2803 | struct address_space *mapping = file->f_mapping;
|
| 2804 | struct inode *inode = mapping->host;
|
| 2805 |
|
| 2806 | if (iocb->ki_flags & IOCB_NOWAIT) {
|
| 2807 | if (filemap_range_needs_writeback(mapping, iocb->ki_pos,
|
| 2808 | iocb->ki_pos + count - 1))
|
| 2809 | return -EAGAIN;
|
| 2810 | } else {
|
| 2811 | retval = filemap_write_and_wait_range(mapping,
|
| 2812 | iocb->ki_pos,
|
| 2813 | iocb->ki_pos + count - 1);
|
| 2814 | if (retval < 0)
|
| 2815 | return retval;
|
| 2816 | }
|
| 2817 |
|
| 2818 | file_accessed(file);
|
| 2819 |
|
| 2820 | retval = mapping->a_ops->direct_IO(iocb, iter);
|
| 2821 | if (retval >= 0) {
|
| 2822 | iocb->ki_pos += retval;
|
| 2823 | count -= retval;
|
| 2824 | }
|
| 2825 | if (retval != -EIOCBQUEUED)
|
| 2826 | iov_iter_revert(iter, count - iov_iter_count(iter));
|
| 2827 |
|
| 2828 | |
| 2829 | * Btrfs can have a short DIO read if we encounter
|
| 2830 | * compressed extents, so if there was an error, or if
|
| 2831 | * we've already read everything we wanted to, or if
|
| 2832 | * there was a short read because we hit EOF, go ahead
|
| 2833 | * and return. Otherwise fallthrough to buffered io for
|
| 2834 | * the rest of the read. Buffered reads will not work for
|
| 2835 | * DAX files, so don't bother trying.
|
| 2836 |
|
| 2837 | if (retval < 0 || !count || IS_DAX(inode))
|
| 2838 | return retval;
|
| 2839 | if (iocb->ki_pos >= i_size_read(inode))
|
| 2840 | return retval;
|
| 2841 | }
|
| 2842 |
|
| 2843 | return filemap_read(iocb, iter, retval);
|
| 2844 | }
|
| 2845 | EXPORT_SYMBOL(generic_file_read_iter);
|
| 2846 |
|
| 2847 | |
| 2848 | * Splice subpages from a folio into a pipe.
|
| 2849 |
|
| 2850 | size_t splice_folio_into_pipe(struct pipe_inode_info *pipe,
|
| 2851 | struct folio *folio, loff_t fpos, size_t size)
|
| 2852 | {
|
| 2853 | struct page *page;
|
| 2854 | size_t spliced = 0, offset = offset_in_folio(folio, fpos);
|
| 2855 |
|
| 2856 | page = folio_page(folio, offset / PAGE_SIZE);
|
| 2857 | size = min(size, folio_size(folio) - offset);
|
| 2858 | offset %= PAGE_SIZE;
|
| 2859 |
|
| 2860 | while (spliced < size &&
|
| 2861 | !pipe_full(pipe->head, pipe->tail, pipe->max_usage)) {
|
| 2862 | struct pipe_buffer *buf = pipe_head_buf(pipe);
|
| 2863 | size_t part = min_t(size_t, PAGE_SIZE - offset, size - spliced);
|
| 2864 |
|
| 2865 | *buf = (struct pipe_buffer) {
|
| 2866 | .ops = &page_cache_pipe_buf_ops,
|
| 2867 | .page = page,
|
| 2868 | .offset = offset,
|
| 2869 | .len = part,
|
| 2870 | };
|
| 2871 | folio_get(folio);
|
| 2872 | pipe->head++;
|
| 2873 | page++;
|
| 2874 | spliced += part;
|
| 2875 | offset = 0;
|
| 2876 | }
|
| 2877 |
|
| 2878 | return spliced;
|
| 2879 | }
|
| 2880 |
|
| 2881 | |
| 2882 | * Splice folios from the pagecache of a buffered (ie. non-O_DIRECT) file into
|
| 2883 | * a pipe.
|
| 2884 |
|
| 2885 | ssize_t filemap_splice_read(struct file *in, loff_t *ppos,
|
| 2886 | struct pipe_inode_info *pipe,
|
| 2887 | size_t len, unsigned int flags)
|
| 2888 | {
|
| 2889 | struct folio_batch fbatch;
|
| 2890 | struct kiocb iocb;
|
| 2891 | size_t total_spliced = 0, used, npages;
|
| 2892 | loff_t isize, end_offset;
|
| 2893 | bool writably_mapped;
|
| 2894 | int i, error = 0;
|
| 2895 |
|
| 2896 | init_sync_kiocb(&iocb, in);
|
| 2897 | iocb.ki_pos = *ppos;
|
| 2898 |
|
| 2899 |
|
| 2900 | used = pipe_occupancy(pipe->head, pipe->tail);
|
| 2901 | npages = max_t(ssize_t, pipe->max_usage - used, 0);
|
| 2902 | len = min_t(size_t, len, npages * PAGE_SIZE);
|
| 2903 |
|
| 2904 | folio_batch_init(&fbatch);
|
| 2905 |
|
| 2906 | do {
|
| 2907 | cond_resched();
|
| 2908 |
|
| 2909 | if (*ppos >= i_size_read(file_inode(in)))
|
| 2910 | break;
|
| 2911 |
|
| 2912 | iocb.ki_pos = *ppos;
|
| 2913 | error = filemap_get_pages(&iocb, len, &fbatch, true);
|
| 2914 | if (error < 0)
|
| 2915 | break;
|
| 2916 |
|
| 2917 | |
| 2918 | * i_size must be checked after we know the pages are Uptodate.
|
| 2919 | *
|
| 2920 | * Checking i_size after the check allows us to calculate
|
| 2921 | * the correct value for "nr", which means the zero-filled
|
| 2922 | * part of the page is not copied back to userspace (unless
|
| 2923 | * another truncate extends the file - this is desired though).
|
| 2924 |
|
| 2925 | isize = i_size_read(file_inode(in));
|
| 2926 | if (unlikely(*ppos >= isize))
|
| 2927 | break;
|
| 2928 | end_offset = min_t(loff_t, isize, *ppos + len);
|
| 2929 |
|
| 2930 | |
| 2931 | * Once we start copying data, we don't want to be touching any
|
| 2932 | * cachelines that might be contended:
|
| 2933 |
|
| 2934 | writably_mapped = mapping_writably_mapped(in->f_mapping);
|
| 2935 |
|
| 2936 | for (i = 0; i < folio_batch_count(&fbatch); i++) {
|
| 2937 | struct folio *folio = fbatch.folios[i];
|
| 2938 | size_t n;
|
| 2939 |
|
| 2940 | if (folio_pos(folio) >= end_offset)
|
| 2941 | goto out;
|
| 2942 | folio_mark_accessed(folio);
|
| 2943 |
|
| 2944 | |
| 2945 | * If users can be writing to this folio using arbitrary
|
| 2946 | * virtual addresses, take care of potential aliasing
|
| 2947 | * before reading the folio on the kernel side.
|
| 2948 |
|
| 2949 | if (writably_mapped)
|
| 2950 | flush_dcache_folio(folio);
|
| 2951 |
|
| 2952 | n = min_t(loff_t, len, isize - *ppos);
|
| 2953 | n = splice_folio_into_pipe(pipe, folio, *ppos, n);
|
| 2954 | if (!n)
|
| 2955 | goto out;
|
| 2956 | len -= n;
|
| 2957 | total_spliced += n;
|
| 2958 | *ppos += n;
|
| 2959 | in->f_ra.prev_pos = *ppos;
|
| 2960 | if (pipe_full(pipe->head, pipe->tail, pipe->max_usage))
|
| 2961 | goto out;
|
| 2962 | }
|
| 2963 |
|
| 2964 | folio_batch_release(&fbatch);
|
| 2965 | } while (len);
|
| 2966 |
|
| 2967 | out:
|
| 2968 | folio_batch_release(&fbatch);
|
| 2969 | file_accessed(in);
|
| 2970 |
|
| 2971 | return total_spliced ? total_spliced : error;
|
| 2972 | }
|
| 2973 | EXPORT_SYMBOL(filemap_splice_read);
|
| 2974 |
|
| 2975 | static inline loff_t folio_seek_hole_data(struct xa_state *xas,
|
| 2976 | struct address_space *mapping, struct folio *folio,
|
| 2977 | loff_t start, loff_t end, bool seek_data)
|
| 2978 | {
|
| 2979 | const struct address_space_operations *ops = mapping->a_ops;
|
| 2980 | size_t offset, bsz = i_blocksize(mapping->host);
|
| 2981 |
|
| 2982 | if (xa_is_value(folio) || folio_test_uptodate(folio))
|
| 2983 | return seek_data ? start : end;
|
| 2984 | if (!ops->is_partially_uptodate)
|
| 2985 | return seek_data ? end : start;
|
| 2986 |
|
| 2987 | xas_pause(xas);
|
| 2988 | rcu_read_unlock();
|
| 2989 | folio_lock(folio);
|
| 2990 | if (unlikely(folio->mapping != mapping))
|
| 2991 | goto unlock;
|
| 2992 |
|
| 2993 | offset = offset_in_folio(folio, start) & ~(bsz - 1);
|
| 2994 |
|
| 2995 | do {
|
| 2996 | if (ops->is_partially_uptodate(folio, offset, bsz) ==
|
| 2997 | seek_data)
|
| 2998 | break;
|
| 2999 | start = (start + bsz) & ~(bsz - 1);
|
| 3000 | offset += bsz;
|
| 3001 | } while (offset < folio_size(folio));
|
| 3002 | unlock:
|
| 3003 | folio_unlock(folio);
|
| 3004 | rcu_read_lock();
|
| 3005 | return start;
|
| 3006 | }
|
| 3007 |
|
| 3008 | static inline size_t seek_folio_size(struct xa_state *xas, struct folio *folio)
|
| 3009 | {
|
| 3010 | if (xa_is_value(folio))
|
| 3011 | return PAGE_SIZE << xa_get_order(xas->xa, xas->xa_index);
|
| 3012 | return folio_size(folio);
|
| 3013 | }
|
| 3014 |
|
| 3015 | |
| 3016 | * mapping_seek_hole_data - Seek for SEEK_DATA / SEEK_HOLE in the page cache.
|
| 3017 | * @mapping: Address space to search.
|
| 3018 | * @start: First byte to consider.
|
| 3019 | * @end: Limit of search (exclusive).
|
| 3020 | * @whence: Either SEEK_HOLE or SEEK_DATA.
|
| 3021 | *
|
| 3022 | * If the page cache knows which blocks contain holes and which blocks
|
| 3023 | * contain data, your filesystem can use this function to implement
|
| 3024 | * SEEK_HOLE and SEEK_DATA. This is useful for filesystems which are
|
| 3025 | * entirely memory-based such as tmpfs, and filesystems which support
|
| 3026 | * unwritten extents.
|
| 3027 | *
|
| 3028 | * Return: The requested offset on success, or -ENXIO if @whence specifies
|
| 3029 | * SEEK_DATA and there is no data after @start. There is an implicit hole
|
| 3030 | * after @end - 1, so SEEK_HOLE returns @end if all the bytes between @start
|
| 3031 | * and @end contain data.
|
| 3032 |
|
| 3033 | loff_t mapping_seek_hole_data(struct address_space *mapping, loff_t start,
|
| 3034 | loff_t end, int whence)
|
| 3035 | {
|
| 3036 | XA_STATE(xas, &mapping->i_pages, start >> PAGE_SHIFT);
|
| 3037 | pgoff_t max = (end - 1) >> PAGE_SHIFT;
|
| 3038 | bool seek_data = (whence == SEEK_DATA);
|
| 3039 | struct folio *folio;
|
| 3040 |
|
| 3041 | if (end <= start)
|
| 3042 | return -ENXIO;
|
| 3043 |
|
| 3044 | rcu_read_lock();
|
| 3045 | while ((folio = find_get_entry(&xas, max, XA_PRESENT))) {
|
| 3046 | loff_t pos = (u64)xas.xa_index << PAGE_SHIFT;
|
| 3047 | size_t seek_size;
|
| 3048 |
|
| 3049 | if (start < pos) {
|
| 3050 | if (!seek_data)
|
| 3051 | goto unlock;
|
| 3052 | start = pos;
|
| 3053 | }
|
| 3054 |
|
| 3055 | seek_size = seek_folio_size(&xas, folio);
|
| 3056 | pos = round_up((u64)pos + 1, seek_size);
|
| 3057 | start = folio_seek_hole_data(&xas, mapping, folio, start, pos,
|
| 3058 | seek_data);
|
| 3059 | if (start < pos)
|
| 3060 | goto unlock;
|
| 3061 | if (start >= end)
|
| 3062 | break;
|
| 3063 | if (seek_size > PAGE_SIZE)
|
| 3064 | xas_set(&xas, pos >> PAGE_SHIFT);
|
| 3065 | if (!xa_is_value(folio))
|
| 3066 | folio_put(folio);
|
| 3067 | }
|
| 3068 | if (seek_data)
|
| 3069 | start = -ENXIO;
|
| 3070 | unlock:
|
| 3071 | rcu_read_unlock();
|
| 3072 | if (folio && !xa_is_value(folio))
|
| 3073 | folio_put(folio);
|
| 3074 | if (start > end)
|
| 3075 | return end;
|
| 3076 | return start;
|
| 3077 | }
|
| 3078 |
|
| 3079 | #ifdef CONFIG_MMU
|
| 3080 | #define MMAP_LOTSAMISS (100)
|
| 3081 | |
| 3082 | * lock_folio_maybe_drop_mmap - lock the page, possibly dropping the mmap_lock
|
| 3083 | * @vmf - the vm_fault for this fault.
|
| 3084 | * @folio - the folio to lock.
|
| 3085 | * @fpin - the pointer to the file we may pin (or is already pinned).
|
| 3086 | *
|
| 3087 | * This works similar to lock_folio_or_retry in that it can drop the
|
| 3088 | * mmap_lock. It differs in that it actually returns the folio locked
|
| 3089 | * if it returns 1 and 0 if it couldn't lock the folio. If we did have
|
| 3090 | * to drop the mmap_lock then fpin will point to the pinned file and
|
| 3091 | * needs to be fput()'ed at a later point.
|
| 3092 |
|
| 3093 | static int lock_folio_maybe_drop_mmap(struct vm_fault *vmf, struct folio *folio,
|
| 3094 | struct file **fpin)
|
| 3095 | {
|
| 3096 | if (folio_trylock(folio))
|
| 3097 | return 1;
|
| 3098 |
|
| 3099 | |
| 3100 | * NOTE! This will make us return with VM_FAULT_RETRY, but with
|
| 3101 | * the mmap_lock still held. That's how FAULT_FLAG_RETRY_NOWAIT
|
| 3102 | * is supposed to work. We have way too many special cases..
|
| 3103 |
|
| 3104 | if (vmf->flags & FAULT_FLAG_RETRY_NOWAIT)
|
| 3105 | return 0;
|
| 3106 |
|
| 3107 | *fpin = maybe_unlock_mmap_for_io(vmf, *fpin);
|
| 3108 | if (vmf->flags & FAULT_FLAG_KILLABLE) {
|
| 3109 | if (__folio_lock_killable(folio)) {
|
| 3110 | |
| 3111 | * We didn't have the right flags to drop the mmap_lock,
|
| 3112 | * but all fault_handlers only check for fatal signals
|
| 3113 | * if we return VM_FAULT_RETRY, so we need to drop the
|
| 3114 | * mmap_lock here and return 0 if we don't have a fpin.
|
| 3115 |
|
| 3116 | if (*fpin == NULL)
|
| 3117 | mmap_read_unlock(vmf->vma->vm_mm);
|
| 3118 | return 0;
|
| 3119 | }
|
| 3120 | } else
|
| 3121 | __folio_lock(folio);
|
| 3122 |
|
| 3123 | return 1;
|
| 3124 | }
|
| 3125 |
|
| 3126 | |
| 3127 | * Synchronous readahead happens when we don't even find a page in the page
|
| 3128 | * cache at all. We don't want to perform IO under the mmap sem, so if we have
|
| 3129 | * to drop the mmap sem we return the file that was pinned in order for us to do
|
| 3130 | * that. If we didn't pin a file then we return NULL. The file that is
|
| 3131 | * returned needs to be fput()'ed when we're done with it.
|
| 3132 |
|
| 3133 | static struct file *do_sync_mmap_readahead(struct vm_fault *vmf)
|
| 3134 | {
|
| 3135 | struct file *file = vmf->vma->vm_file;
|
| 3136 | struct file_ra_state *ra = &file->f_ra;
|
| 3137 | struct address_space *mapping = file->f_mapping;
|
| 3138 | DEFINE_READAHEAD(ractl, file, ra, mapping, vmf->pgoff);
|
| 3139 | struct file *fpin = NULL;
|
| 3140 | unsigned long vm_flags = vmf->vma->vm_flags;
|
| 3141 | unsigned int mmap_miss;
|
| 3142 |
|
| 3143 | #ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
| 3144 |
|
| 3145 | if (vm_flags & VM_HUGEPAGE) {
|
| 3146 | fpin = maybe_unlock_mmap_for_io(vmf, fpin);
|
| 3147 | ractl._index &= ~((unsigned long)HPAGE_PMD_NR - 1);
|
| 3148 | ra->size = HPAGE_PMD_NR;
|
| 3149 | |
| 3150 | * Fetch two PMD folios, so we get the chance to actually
|
| 3151 | * readahead, unless we've been told not to.
|
| 3152 |
|
| 3153 | if (!(vm_flags & VM_RAND_READ))
|
| 3154 | ra->size *= 2;
|
| 3155 | ra->async_size = HPAGE_PMD_NR;
|
| 3156 | page_cache_ra_order(&ractl, ra, HPAGE_PMD_ORDER);
|
| 3157 | return fpin;
|
| 3158 | }
|
| 3159 | #endif
|
| 3160 |
|
| 3161 |
|
| 3162 | if (vm_flags & VM_RAND_READ)
|
| 3163 | return fpin;
|
| 3164 | if (!ra->ra_pages)
|
| 3165 | return fpin;
|
| 3166 |
|
| 3167 | if (vm_flags & VM_SEQ_READ) {
|
| 3168 | fpin = maybe_unlock_mmap_for_io(vmf, fpin);
|
| 3169 | page_cache_sync_ra(&ractl, ra->ra_pages);
|
| 3170 | return fpin;
|
| 3171 | }
|
| 3172 |
|
| 3173 |
|
| 3174 | mmap_miss = READ_ONCE(ra->mmap_miss);
|
| 3175 | if (mmap_miss < MMAP_LOTSAMISS * 10)
|
| 3176 | WRITE_ONCE(ra->mmap_miss, ++mmap_miss);
|
| 3177 |
|
| 3178 | |
| 3179 | * Do we miss much more than hit in this file? If so,
|
| 3180 | * stop bothering with read-ahead. It will only hurt.
|
| 3181 |
|
| 3182 | if (mmap_miss > MMAP_LOTSAMISS)
|
| 3183 | return fpin;
|
| 3184 |
|
| 3185 | |
| 3186 | * mmap read-around
|
| 3187 |
|
| 3188 | fpin = maybe_unlock_mmap_for_io(vmf, fpin);
|
| 3189 | ra->start = max_t(long, 0, vmf->pgoff - ra->ra_pages / 2);
|
| 3190 | ra->size = ra->ra_pages;
|
| 3191 | ra->async_size = ra->ra_pages / 4;
|
| 3192 | ractl._index = ra->start;
|
| 3193 | page_cache_ra_order(&ractl, ra, 0);
|
| 3194 | return fpin;
|
| 3195 | }
|
| 3196 |
|
| 3197 | |
| 3198 | * Asynchronous readahead happens when we find the page and PG_readahead,
|
| 3199 | * so we want to possibly extend the readahead further. We return the file that
|
| 3200 | * was pinned if we have to drop the mmap_lock in order to do IO.
|
| 3201 |
|
| 3202 | static struct file *do_async_mmap_readahead(struct vm_fault *vmf,
|
| 3203 | struct folio *folio)
|
| 3204 | {
|
| 3205 | struct file *file = vmf->vma->vm_file;
|
| 3206 | struct file_ra_state *ra = &file->f_ra;
|
| 3207 | DEFINE_READAHEAD(ractl, file, ra, file->f_mapping, vmf->pgoff);
|
| 3208 | struct file *fpin = NULL;
|
| 3209 | unsigned int mmap_miss;
|
| 3210 |
|
| 3211 |
|
| 3212 | if (vmf->vma->vm_flags & VM_RAND_READ || !ra->ra_pages)
|
| 3213 | return fpin;
|
| 3214 |
|
| 3215 | mmap_miss = READ_ONCE(ra->mmap_miss);
|
| 3216 | if (mmap_miss)
|
| 3217 | WRITE_ONCE(ra->mmap_miss, --mmap_miss);
|
| 3218 |
|
| 3219 | if (folio_test_readahead(folio)) {
|
| 3220 | fpin = maybe_unlock_mmap_for_io(vmf, fpin);
|
| 3221 | page_cache_async_ra(&ractl, folio, ra->ra_pages);
|
| 3222 | }
|
| 3223 | return fpin;
|
| 3224 | }
|
| 3225 |
|
| 3226 | |
| 3227 | * filemap_fault - read in file data for page fault handling
|
| 3228 | * @vmf: struct vm_fault containing details of the fault
|
| 3229 | *
|
| 3230 | * filemap_fault() is invoked via the vma operations vector for a
|
| 3231 | * mapped memory region to read in file data during a page fault.
|
| 3232 | *
|
| 3233 | * The goto's are kind of ugly, but this streamlines the normal case of having
|
| 3234 | * it in the page cache, and handles the special cases reasonably without
|
| 3235 | * having a lot of duplicated code.
|
| 3236 | *
|
| 3237 | * vma->vm_mm->mmap_lock must be held on entry.
|
| 3238 | *
|
| 3239 | * If our return value has VM_FAULT_RETRY set, it's because the mmap_lock
|
| 3240 | * may be dropped before doing I/O or by lock_folio_maybe_drop_mmap().
|
| 3241 | *
|
| 3242 | * If our return value does not have VM_FAULT_RETRY set, the mmap_lock
|
| 3243 | * has not been released.
|
| 3244 | *
|
| 3245 | * We never return with VM_FAULT_RETRY and a bit from VM_FAULT_ERROR set.
|
| 3246 | *
|
| 3247 | * Return: bitwise-OR of %VM_FAULT_ codes.
|
| 3248 |
|
| 3249 | vm_fault_t filemap_fault(struct vm_fault *vmf)
|
| 3250 | {
|
| 3251 | int error;
|
| 3252 | struct file *file = vmf->vma->vm_file;
|
| 3253 | struct file *fpin = NULL;
|
| 3254 | struct address_space *mapping = file->f_mapping;
|
| 3255 | struct inode *inode = mapping->host;
|
| 3256 | pgoff_t max_idx, index = vmf->pgoff;
|
| 3257 | struct folio *folio;
|
| 3258 | vm_fault_t ret = 0;
|
| 3259 | bool mapping_locked = false;
|
| 3260 |
|
| 3261 | max_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
|
| 3262 | if (unlikely(index >= max_idx))
|
| 3263 | return VM_FAULT_SIGBUS;
|
| 3264 |
|
| 3265 | |
| 3266 | * Do we have something in the page cache already?
|
| 3267 |
|
| 3268 | folio = filemap_get_folio(mapping, index);
|
| 3269 | if (likely(!IS_ERR(folio))) {
|
| 3270 | |
| 3271 | * We found the page, so try async readahead before waiting for
|
| 3272 | * the lock.
|
| 3273 |
|
| 3274 | if (!(vmf->flags & FAULT_FLAG_TRIED))
|
| 3275 | fpin = do_async_mmap_readahead(vmf, folio);
|
| 3276 | if (unlikely(!folio_test_uptodate(folio))) {
|
| 3277 | filemap_invalidate_lock_shared(mapping);
|
| 3278 | mapping_locked = true;
|
| 3279 | }
|
| 3280 | } else {
|
| 3281 |
|
| 3282 | count_vm_event(PGMAJFAULT);
|
| 3283 | count_memcg_event_mm(vmf->vma->vm_mm, PGMAJFAULT);
|
| 3284 | ret = VM_FAULT_MAJOR;
|
| 3285 | fpin = do_sync_mmap_readahead(vmf);
|
| 3286 | retry_find:
|
| 3287 | |
| 3288 | * See comment in filemap_create_folio() why we need
|
| 3289 | * invalidate_lock
|
| 3290 |
|
| 3291 | if (!mapping_locked) {
|
| 3292 | filemap_invalidate_lock_shared(mapping);
|
| 3293 | mapping_locked = true;
|
| 3294 | }
|
| 3295 | folio = __filemap_get_folio(mapping, index,
|
| 3296 | FGP_CREAT|FGP_FOR_MMAP,
|
| 3297 | vmf->gfp_mask);
|
| 3298 | if (IS_ERR(folio)) {
|
| 3299 | if (fpin)
|
| 3300 | goto out_retry;
|
| 3301 | filemap_invalidate_unlock_shared(mapping);
|
| 3302 | return VM_FAULT_OOM;
|
| 3303 | }
|
| 3304 | }
|
| 3305 |
|
| 3306 | if (!lock_folio_maybe_drop_mmap(vmf, folio, &fpin))
|
| 3307 | goto out_retry;
|
| 3308 |
|
| 3309 |
|
| 3310 | if (unlikely(folio->mapping != mapping)) {
|
| 3311 | folio_unlock(folio);
|
| 3312 | folio_put(folio);
|
| 3313 | goto retry_find;
|
| 3314 | }
|
| 3315 | VM_BUG_ON_FOLIO(!folio_contains(folio, index), folio);
|
| 3316 |
|
| 3317 | |
| 3318 | * We have a locked page in the page cache, now we need to check
|
| 3319 | * that it's up-to-date. If not, it is going to be due to an error.
|
| 3320 |
|
| 3321 | if (unlikely(!folio_test_uptodate(folio))) {
|
| 3322 | |
| 3323 | * The page was in cache and uptodate and now it is not.
|
| 3324 | * Strange but possible since we didn't hold the page lock all
|
| 3325 | * the time. Let's drop everything get the invalidate lock and
|
| 3326 | * try again.
|
| 3327 |
|
| 3328 | if (!mapping_locked) {
|
| 3329 | folio_unlock(folio);
|
| 3330 | folio_put(folio);
|
| 3331 | goto retry_find;
|
| 3332 | }
|
| 3333 | goto page_not_uptodate;
|
| 3334 | }
|
| 3335 |
|
| 3336 | |
| 3337 | * We've made it this far and we had to drop our mmap_lock, now is the
|
| 3338 | * time to return to the upper layer and have it re-find the vma and
|
| 3339 | * redo the fault.
|
| 3340 |
|
| 3341 | if (fpin) {
|
| 3342 | folio_unlock(folio);
|
| 3343 | goto out_retry;
|
| 3344 | }
|
| 3345 | if (mapping_locked)
|
| 3346 | filemap_invalidate_unlock_shared(mapping);
|
| 3347 |
|
| 3348 | |
| 3349 | * Found the page and have a reference on it.
|
| 3350 | * We must recheck i_size under page lock.
|
| 3351 |
|
| 3352 | max_idx = DIV_ROUND_UP(i_size_read(inode), PAGE_SIZE);
|
| 3353 | if (unlikely(index >= max_idx)) {
|
| 3354 | folio_unlock(folio);
|
| 3355 | folio_put(folio);
|
| 3356 | return VM_FAULT_SIGBUS;
|
| 3357 | }
|
| 3358 |
|
| 3359 | vmf->page = folio_file_page(folio, index);
|
| 3360 | return ret | VM_FAULT_LOCKED;
|
| 3361 |
|
| 3362 | page_not_uptodate:
|
| 3363 | |
| 3364 | * Umm, take care of errors if the page isn't up-to-date.
|
| 3365 | * Try to re-read it _once_. We do this synchronously,
|
| 3366 | * because there really aren't any performance issues here
|
| 3367 | * and we need to check for errors.
|
| 3368 |
|
| 3369 | fpin = maybe_unlock_mmap_for_io(vmf, fpin);
|
| 3370 | error = filemap_read_folio(file, mapping->a_ops->read_folio, folio);
|
| 3371 | if (fpin)
|
| 3372 | goto out_retry;
|
| 3373 | folio_put(folio);
|
| 3374 |
|
| 3375 | if (!error || error == AOP_TRUNCATED_PAGE)
|
| 3376 | goto retry_find;
|
| 3377 | filemap_invalidate_unlock_shared(mapping);
|
| 3378 |
|
| 3379 | return VM_FAULT_SIGBUS;
|
| 3380 |
|
| 3381 | out_retry:
|
| 3382 | |
| 3383 | * We dropped the mmap_lock, we need to return to the fault handler to
|
| 3384 | * re-find the vma and come back and find our hopefully still populated
|
| 3385 | * page.
|
| 3386 |
|
| 3387 | if (!IS_ERR(folio))
|
| 3388 | folio_put(folio);
|
| 3389 | if (mapping_locked)
|
| 3390 | filemap_invalidate_unlock_shared(mapping);
|
| 3391 | if (fpin)
|
| 3392 | fput(fpin);
|
| 3393 | return ret | VM_FAULT_RETRY;
|
| 3394 | }
|
| 3395 | EXPORT_SYMBOL(filemap_fault);
|
| 3396 |
|
| 3397 | static bool filemap_map_pmd(struct vm_fault *vmf, struct folio *folio,
|
| 3398 | pgoff_t start)
|
| 3399 | {
|
| 3400 | struct mm_struct *mm = vmf->vma->vm_mm;
|
| 3401 |
|
| 3402 |
|
| 3403 | if (pmd_trans_huge(*vmf->pmd)) {
|
| 3404 | folio_unlock(folio);
|
| 3405 | folio_put(folio);
|
| 3406 | return true;
|
| 3407 | }
|
| 3408 |
|
| 3409 | if (pmd_none(*vmf->pmd) && folio_test_pmd_mappable(folio)) {
|
| 3410 | struct page *page = folio_file_page(folio, start);
|
| 3411 | vm_fault_t ret = do_set_pmd(vmf, page);
|
| 3412 | if (!ret) {
|
| 3413 |
|
| 3414 | folio_unlock(folio);
|
| 3415 | return true;
|
| 3416 | }
|
| 3417 | }
|
| 3418 |
|
| 3419 | if (pmd_none(*vmf->pmd))
|
| 3420 | pmd_install(mm, vmf->pmd, &vmf->prealloc_pte);
|
| 3421 |
|
| 3422 |
|
| 3423 | if (pmd_devmap_trans_unstable(vmf->pmd)) {
|
| 3424 | folio_unlock(folio);
|
| 3425 | folio_put(folio);
|
| 3426 | return true;
|
| 3427 | }
|
| 3428 |
|
| 3429 | return false;
|
| 3430 | }
|
| 3431 |
|
| 3432 | static struct folio *next_uptodate_page(struct folio *folio,
|
| 3433 | struct address_space *mapping,
|
| 3434 | struct xa_state *xas, pgoff_t end_pgoff)
|
| 3435 | {
|
| 3436 | unsigned long max_idx;
|
| 3437 |
|
| 3438 | do {
|
| 3439 | if (!folio)
|
| 3440 | return NULL;
|
| 3441 | if (xas_retry(xas, folio))
|
| 3442 | continue;
|
| 3443 | if (xa_is_value(folio))
|
| 3444 | continue;
|
| 3445 | if (folio_test_locked(folio))
|
| 3446 | continue;
|
| 3447 | if (!folio_try_get_rcu(folio))
|
| 3448 | continue;
|
| 3449 |
|
| 3450 | if (unlikely(folio != xas_reload(xas)))
|
| 3451 | goto skip;
|
| 3452 | if (!folio_test_uptodate(folio) || folio_test_readahead(folio))
|
| 3453 | goto skip;
|
| 3454 | if (!folio_trylock(folio))
|
| 3455 | goto skip;
|
| 3456 | if (folio->mapping != mapping)
|
| 3457 | goto unlock;
|
| 3458 | if (!folio_test_uptodate(folio))
|
| 3459 | goto unlock;
|
| 3460 | max_idx = DIV_ROUND_UP(i_size_read(mapping->host), PAGE_SIZE);
|
| 3461 | if (xas->xa_index >= max_idx)
|
| 3462 | goto unlock;
|
| 3463 | return folio;
|
| 3464 | unlock:
|
| 3465 | folio_unlock(folio);
|
| 3466 | skip:
|
| 3467 | folio_put(folio);
|
| 3468 | } while ((folio = xas_next_entry(xas, end_pgoff)) != NULL);
|
| 3469 |
|
| 3470 | return NULL;
|
| 3471 | }
|
| 3472 |
|
| 3473 | static inline struct folio *first_map_page(struct address_space *mapping,
|
| 3474 | struct xa_state *xas,
|
| 3475 | pgoff_t end_pgoff)
|
| 3476 | {
|
| 3477 | return next_uptodate_page(xas_find(xas, end_pgoff),
|
| 3478 | mapping, xas, end_pgoff);
|
| 3479 | }
|
| 3480 |
|
| 3481 | static inline struct folio *next_map_page(struct address_space *mapping,
|
| 3482 | struct xa_state *xas,
|
| 3483 | pgoff_t end_pgoff)
|
| 3484 | {
|
| 3485 | return next_uptodate_page(xas_next_entry(xas, end_pgoff),
|
| 3486 | mapping, xas, end_pgoff);
|
| 3487 | }
|
| 3488 |
|
| 3489 | vm_fault_t filemap_map_pages(struct vm_fault *vmf,
|
| 3490 | pgoff_t start_pgoff, pgoff_t end_pgoff)
|
| 3491 | {
|
| 3492 | struct vm_area_struct *vma = vmf->vma;
|
| 3493 | struct file *file = vma->vm_file;
|
| 3494 | struct address_space *mapping = file->f_mapping;
|
| 3495 | pgoff_t last_pgoff = start_pgoff;
|
| 3496 | unsigned long addr;
|
| 3497 | XA_STATE(xas, &mapping->i_pages, start_pgoff);
|
| 3498 | struct folio *folio;
|
| 3499 | struct page *page;
|
| 3500 | unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss);
|
| 3501 | vm_fault_t ret = 0;
|
| 3502 |
|
| 3503 | rcu_read_lock();
|
| 3504 | folio = first_map_page(mapping, &xas, end_pgoff);
|
| 3505 | if (!folio)
|
| 3506 | goto out;
|
| 3507 |
|
| 3508 | if (filemap_map_pmd(vmf, folio, start_pgoff)) {
|
| 3509 | ret = VM_FAULT_NOPAGE;
|
| 3510 | goto out;
|
| 3511 | }
|
| 3512 |
|
| 3513 | addr = vma->vm_start + ((start_pgoff - vma->vm_pgoff) << PAGE_SHIFT);
|
| 3514 | vmf->pte = pte_offset_map_lock(vma->vm_mm, vmf->pmd, addr, &vmf->ptl);
|
| 3515 | do {
|
| 3516 | again:
|
| 3517 | page = folio_file_page(folio, xas.xa_index);
|
| 3518 | if (PageHWPoison(page))
|
| 3519 | goto unlock;
|
| 3520 |
|
| 3521 | if (mmap_miss > 0)
|
| 3522 | mmap_miss--;
|
| 3523 |
|
| 3524 | addr += (xas.xa_index - last_pgoff) << PAGE_SHIFT;
|
| 3525 | vmf->pte += xas.xa_index - last_pgoff;
|
| 3526 | last_pgoff = xas.xa_index;
|
| 3527 |
|
| 3528 | |
| 3529 | * NOTE: If there're PTE markers, we'll leave them to be
|
| 3530 | * handled in the specific fault path, and it'll prohibit the
|
| 3531 | * fault-around logic.
|
| 3532 |
|
| 3533 | if (!pte_none(*vmf->pte))
|
| 3534 | goto unlock;
|
| 3535 |
|
| 3536 |
|
| 3537 | if (vmf->address == addr)
|
| 3538 | ret = VM_FAULT_NOPAGE;
|
| 3539 |
|
| 3540 | do_set_pte(vmf, page, addr);
|
| 3541 |
|
| 3542 | update_mmu_cache(vma, addr, vmf->pte);
|
| 3543 | if (folio_more_pages(folio, xas.xa_index, end_pgoff)) {
|
| 3544 | xas.xa_index++;
|
| 3545 | folio_ref_inc(folio);
|
| 3546 | goto again;
|
| 3547 | }
|
| 3548 | folio_unlock(folio);
|
| 3549 | continue;
|
| 3550 | unlock:
|
| 3551 | if (folio_more_pages(folio, xas.xa_index, end_pgoff)) {
|
| 3552 | xas.xa_index++;
|
| 3553 | goto again;
|
| 3554 | }
|
| 3555 | folio_unlock(folio);
|
| 3556 | folio_put(folio);
|
| 3557 | } while ((folio = next_map_page(mapping, &xas, end_pgoff)) != NULL);
|
| 3558 | pte_unmap_unlock(vmf->pte, vmf->ptl);
|
| 3559 | out:
|
| 3560 | rcu_read_unlock();
|
| 3561 | WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss);
|
| 3562 | return ret;
|
| 3563 | }
|
| 3564 | EXPORT_SYMBOL(filemap_map_pages);
|
| 3565 |
|
| 3566 | vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf)
|
| 3567 | {
|
| 3568 | struct address_space *mapping = vmf->vma->vm_file->f_mapping;
|
| 3569 | struct folio *folio = page_folio(vmf->page);
|
| 3570 | vm_fault_t ret = VM_FAULT_LOCKED;
|
| 3571 |
|
| 3572 | sb_start_pagefault(mapping->host->i_sb);
|
| 3573 | file_update_time(vmf->vma->vm_file);
|
| 3574 | folio_lock(folio);
|
| 3575 | if (folio->mapping != mapping) {
|
| 3576 | folio_unlock(folio);
|
| 3577 | ret = VM_FAULT_NOPAGE;
|
| 3578 | goto out;
|
| 3579 | }
|
| 3580 | |
| 3581 | * We mark the folio dirty already here so that when freeze is in
|
| 3582 | * progress, we are guaranteed that writeback during freezing will
|
| 3583 | * see the dirty folio and writeprotect it again.
|
| 3584 |
|
| 3585 | folio_mark_dirty(folio);
|
| 3586 | folio_wait_stable(folio);
|
| 3587 | out:
|
| 3588 | sb_end_pagefault(mapping->host->i_sb);
|
| 3589 | return ret;
|
| 3590 | }
|
| 3591 |
|
| 3592 | const struct vm_operations_struct generic_file_vm_ops = {
|
| 3593 | .fault = filemap_fault,
|
| 3594 | .map_pages = filemap_map_pages,
|
| 3595 | .page_mkwrite = filemap_page_mkwrite,
|
| 3596 | };
|
| 3597 |
|
| 3598 |
|
| 3599 |
|
| 3600 | int generic_file_mmap(struct file *file, struct vm_area_struct *vma)
|
| 3601 | {
|
| 3602 | struct address_space *mapping = file->f_mapping;
|
| 3603 |
|
| 3604 | if (!mapping->a_ops->read_folio)
|
| 3605 | return -ENOEXEC;
|
| 3606 | file_accessed(file);
|
| 3607 | vma->vm_ops = &generic_file_vm_ops;
|
| 3608 | return 0;
|
| 3609 | }
|
| 3610 |
|
| 3611 | |
| 3612 | * This is for filesystems which do not implement ->writepage.
|
| 3613 |
|
| 3614 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
|
| 3615 | {
|
| 3616 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
|
| 3617 | return -EINVAL;
|
| 3618 | return generic_file_mmap(file, vma);
|
| 3619 | }
|
| 3620 | #else
|
| 3621 | vm_fault_t filemap_page_mkwrite(struct vm_fault *vmf)
|
| 3622 | {
|
| 3623 | return VM_FAULT_SIGBUS;
|
| 3624 | }
|
| 3625 | int generic_file_mmap(struct file *file, struct vm_area_struct *vma)
|
| 3626 | {
|
| 3627 | return -ENOSYS;
|
| 3628 | }
|
| 3629 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
|
| 3630 | {
|
| 3631 | return -ENOSYS;
|
| 3632 | }
|
| 3633 | #endif
|
| 3634 |
|
| 3635 | EXPORT_SYMBOL(filemap_page_mkwrite);
|
| 3636 | EXPORT_SYMBOL(generic_file_mmap);
|
| 3637 | EXPORT_SYMBOL(generic_file_readonly_mmap);
|
| 3638 |
|
| 3639 | static struct folio *do_read_cache_folio(struct address_space *mapping,
|
| 3640 | pgoff_t index, filler_t filler, struct file *file, gfp_t gfp)
|
| 3641 | {
|
| 3642 | struct folio *folio;
|
| 3643 | int err;
|
| 3644 |
|
| 3645 | if (!filler)
|
| 3646 | filler = mapping->a_ops->read_folio;
|
| 3647 | repeat:
|
| 3648 | folio = filemap_get_folio(mapping, index);
|
| 3649 | if (IS_ERR(folio)) {
|
| 3650 | folio = filemap_alloc_folio(gfp, 0);
|
| 3651 | if (!folio)
|
| 3652 | return ERR_PTR(-ENOMEM);
|
| 3653 | err = filemap_add_folio(mapping, folio, index, gfp);
|
| 3654 | if (unlikely(err)) {
|
| 3655 | folio_put(folio);
|
| 3656 | if (err == -EEXIST)
|
| 3657 | goto repeat;
|
| 3658 |
|
| 3659 | return ERR_PTR(err);
|
| 3660 | }
|
| 3661 |
|
| 3662 | goto filler;
|
| 3663 | }
|
| 3664 | if (folio_test_uptodate(folio))
|
| 3665 | goto out;
|
| 3666 |
|
| 3667 | if (!folio_trylock(folio)) {
|
| 3668 | folio_put_wait_locked(folio, TASK_UNINTERRUPTIBLE);
|
| 3669 | goto repeat;
|
| 3670 | }
|
| 3671 |
|
| 3672 |
|
| 3673 | if (!folio->mapping) {
|
| 3674 | folio_unlock(folio);
|
| 3675 | folio_put(folio);
|
| 3676 | goto repeat;
|
| 3677 | }
|
| 3678 |
|
| 3679 |
|
| 3680 | if (folio_test_uptodate(folio)) {
|
| 3681 | folio_unlock(folio);
|
| 3682 | goto out;
|
| 3683 | }
|
| 3684 |
|
| 3685 | filler:
|
| 3686 | err = filemap_read_folio(file, filler, folio);
|
| 3687 | if (err) {
|
| 3688 | folio_put(folio);
|
| 3689 | if (err == AOP_TRUNCATED_PAGE)
|
| 3690 | goto repeat;
|
| 3691 | return ERR_PTR(err);
|
| 3692 | }
|
| 3693 |
|
| 3694 | out:
|
| 3695 | folio_mark_accessed(folio);
|
| 3696 | return folio;
|
| 3697 | }
|
| 3698 |
|
| 3699 | |
| 3700 | * read_cache_folio - Read into page cache, fill it if needed.
|
| 3701 | * @mapping: The address_space to read from.
|
| 3702 | * @index: The index to read.
|
| 3703 | * @filler: Function to perform the read, or NULL to use aops->read_folio().
|
| 3704 | * @file: Passed to filler function, may be NULL if not required.
|
| 3705 | *
|
| 3706 | * Read one page into the page cache. If it succeeds, the folio returned
|
| 3707 | * will contain @index, but it may not be the first page of the folio.
|
| 3708 | *
|
| 3709 | * If the filler function returns an error, it will be returned to the
|
| 3710 | * caller.
|
| 3711 | *
|
| 3712 | * Context: May sleep. Expects mapping->invalidate_lock to be held.
|
| 3713 | * Return: An uptodate folio on success, ERR_PTR() on failure.
|
| 3714 |
|
| 3715 | struct folio *read_cache_folio(struct address_space *mapping, pgoff_t index,
|
| 3716 | filler_t filler, struct file *file)
|
| 3717 | {
|
| 3718 | return do_read_cache_folio(mapping, index, filler, file,
|
| 3719 | mapping_gfp_mask(mapping));
|
| 3720 | }
|
| 3721 | EXPORT_SYMBOL(read_cache_folio);
|
| 3722 |
|
| 3723 | |
| 3724 | * mapping_read_folio_gfp - Read into page cache, using specified allocation flags.
|
| 3725 | * @mapping: The address_space for the folio.
|
| 3726 | * @index: The index that the allocated folio will contain.
|
| 3727 | * @gfp: The page allocator flags to use if allocating.
|
| 3728 | *
|
| 3729 | * This is the same as "read_cache_folio(mapping, index, NULL, NULL)", but with
|
| 3730 | * any new memory allocations done using the specified allocation flags.
|
| 3731 | *
|
| 3732 | * The most likely error from this function is EIO, but ENOMEM is
|
| 3733 | * possible and so is EINTR. If ->read_folio returns another error,
|
| 3734 | * that will be returned to the caller.
|
| 3735 | *
|
| 3736 | * The function expects mapping->invalidate_lock to be already held.
|
| 3737 | *
|
| 3738 | * Return: Uptodate folio on success, ERR_PTR() on failure.
|
| 3739 |
|
| 3740 | struct folio *mapping_read_folio_gfp(struct address_space *mapping,
|
| 3741 | pgoff_t index, gfp_t gfp)
|
| 3742 | {
|
| 3743 | return do_read_cache_folio(mapping, index, NULL, NULL, gfp);
|
| 3744 | }
|
| 3745 | EXPORT_SYMBOL(mapping_read_folio_gfp);
|
| 3746 |
|
| 3747 | static struct page *do_read_cache_page(struct address_space *mapping,
|
| 3748 | pgoff_t index, filler_t *filler, struct file *file, gfp_t gfp)
|
| 3749 | {
|
| 3750 | struct folio *folio;
|
| 3751 |
|
| 3752 | folio = do_read_cache_folio(mapping, index, filler, file, gfp);
|
| 3753 | if (IS_ERR(folio))
|
| 3754 | return &folio->page;
|
| 3755 | return folio_file_page(folio, index);
|
| 3756 | }
|
| 3757 |
|
| 3758 | struct page *read_cache_page(struct address_space *mapping,
|
| 3759 | pgoff_t index, filler_t *filler, struct file *file)
|
| 3760 | {
|
| 3761 | return do_read_cache_page(mapping, index, filler, file,
|
| 3762 | mapping_gfp_mask(mapping));
|
| 3763 | }
|
| 3764 | EXPORT_SYMBOL(read_cache_page);
|
| 3765 |
|
| 3766 | |
| 3767 | * read_cache_page_gfp - read into page cache, using specified page allocation flags.
|
| 3768 | * @mapping: the page's address_space
|
| 3769 | * @index: the page index
|
| 3770 | * @gfp: the page allocator flags to use if allocating
|
| 3771 | *
|
| 3772 | * This is the same as "read_mapping_page(mapping, index, NULL)", but with
|
| 3773 | * any new page allocations done using the specified allocation flags.
|
| 3774 | *
|
| 3775 | * If the page does not get brought uptodate, return -EIO.
|
| 3776 | *
|
| 3777 | * The function expects mapping->invalidate_lock to be already held.
|
| 3778 | *
|
| 3779 | * Return: up to date page on success, ERR_PTR() on failure.
|
| 3780 |
|
| 3781 | struct page *read_cache_page_gfp(struct address_space *mapping,
|
| 3782 | pgoff_t index,
|
| 3783 | gfp_t gfp)
|
| 3784 | {
|
| 3785 | return do_read_cache_page(mapping, index, NULL, NULL, gfp);
|
| 3786 | }
|
| 3787 | EXPORT_SYMBOL(read_cache_page_gfp);
|
| 3788 |
|
| 3789 | |
| 3790 | * Warn about a page cache invalidation failure during a direct I/O write.
|
| 3791 |
|
| 3792 | void dio_warn_stale_pagecache(struct file *filp)
|
| 3793 | {
|
| 3794 | static DEFINE_RATELIMIT_STATE(_rs, 86400 * HZ, DEFAULT_RATELIMIT_BURST);
|
| 3795 | char pathname[128];
|
| 3796 | char *path;
|
| 3797 |
|
| 3798 | errseq_set(&filp->f_mapping->wb_err, -EIO);
|
| 3799 | if (__ratelimit(&_rs)) {
|
| 3800 | path = file_path(filp, pathname, sizeof(pathname));
|
| 3801 | if (IS_ERR(path))
|
| 3802 | path = "(unknown)";
|
| 3803 | pr_crit("Page cache invalidation failure on direct I/O. Possible data corruption due to collision with buffered I/O!\n");
|
| 3804 | pr_crit("File: %s PID: %d Comm: %.20s\n", path, current->pid,
|
| 3805 | current->comm);
|
| 3806 | }
|
| 3807 | }
|
| 3808 |
|
| 3809 | ssize_t
|
| 3810 | generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from)
|
| 3811 | {
|
| 3812 | struct file *file = iocb->ki_filp;
|
| 3813 | struct address_space *mapping = file->f_mapping;
|
| 3814 | struct inode *inode = mapping->host;
|
| 3815 | loff_t pos = iocb->ki_pos;
|
| 3816 | ssize_t written;
|
| 3817 | size_t write_len;
|
| 3818 | pgoff_t end;
|
| 3819 |
|
| 3820 | write_len = iov_iter_count(from);
|
| 3821 | end = (pos + write_len - 1) >> PAGE_SHIFT;
|
| 3822 |
|
| 3823 | if (iocb->ki_flags & IOCB_NOWAIT) {
|
| 3824 |
|
| 3825 | if (filemap_range_has_page(file->f_mapping, pos,
|
| 3826 | pos + write_len - 1))
|
| 3827 | return -EAGAIN;
|
| 3828 | } else {
|
| 3829 | written = filemap_write_and_wait_range(mapping, pos,
|
| 3830 | pos + write_len - 1);
|
| 3831 | if (written)
|
| 3832 | goto out;
|
| 3833 | }
|
| 3834 |
|
| 3835 | |
| 3836 | * After a write we want buffered reads to be sure to go to disk to get
|
| 3837 | * the new data. We invalidate clean cached page from the region we're
|
| 3838 | * about to write. We do this *before* the write so that we can return
|
| 3839 | * without clobbering -EIOCBQUEUED from ->direct_IO().
|
| 3840 |
|
| 3841 | written = invalidate_inode_pages2_range(mapping,
|
| 3842 | pos >> PAGE_SHIFT, end);
|
| 3843 | |
| 3844 | * If a page can not be invalidated, return 0 to fall back
|
| 3845 | * to buffered write.
|
| 3846 |
|
| 3847 | if (written) {
|
| 3848 | if (written == -EBUSY)
|
| 3849 | return 0;
|
| 3850 | goto out;
|
| 3851 | }
|
| 3852 |
|
| 3853 | written = mapping->a_ops->direct_IO(iocb, from);
|
| 3854 |
|
| 3855 | |
| 3856 | * Finally, try again to invalidate clean pages which might have been
|
| 3857 | * cached by non-direct readahead, or faulted in by get_user_pages()
|
| 3858 | * if the source of the write was an mmap'ed region of the file
|
| 3859 | * we're writing. Either one is a pretty crazy thing to do,
|
| 3860 | * so we don't support it 100%. If this invalidation
|
| 3861 | * fails, tough, the write still worked...
|
| 3862 | *
|
| 3863 | * Most of the time we do not need this since dio_complete() will do
|
| 3864 | * the invalidation for us. However there are some file systems that
|
| 3865 | * do not end up with dio_complete() being called, so let's not break
|
| 3866 | * them by removing it completely.
|
| 3867 | *
|
| 3868 | * Noticeable example is a blkdev_direct_IO().
|
| 3869 | *
|
| 3870 | * Skip invalidation for async writes or if mapping has no pages.
|
| 3871 |
|
| 3872 | if (written > 0 && mapping->nrpages &&
|
| 3873 | invalidate_inode_pages2_range(mapping, pos >> PAGE_SHIFT, end))
|
| 3874 | dio_warn_stale_pagecache(file);
|
| 3875 |
|
| 3876 | if (written > 0) {
|
| 3877 | pos += written;
|
| 3878 | write_len -= written;
|
| 3879 | if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
|
| 3880 | i_size_write(inode, pos);
|
| 3881 | mark_inode_dirty(inode);
|
| 3882 | }
|
| 3883 | iocb->ki_pos = pos;
|
| 3884 | }
|
| 3885 | if (written != -EIOCBQUEUED)
|
| 3886 | iov_iter_revert(from, write_len - iov_iter_count(from));
|
| 3887 | out:
|
| 3888 | return written;
|
| 3889 | }
|
| 3890 | EXPORT_SYMBOL(generic_file_direct_write);
|
| 3891 |
|
| 3892 | ssize_t generic_perform_write(struct kiocb *iocb, struct iov_iter *i)
|
| 3893 | {
|
| 3894 | struct file *file = iocb->ki_filp;
|
| 3895 | loff_t pos = iocb->ki_pos;
|
| 3896 | struct address_space *mapping = file->f_mapping;
|
| 3897 | const struct address_space_operations *a_ops = mapping->a_ops;
|
| 3898 | long status = 0;
|
| 3899 | ssize_t written = 0;
|
| 3900 |
|
| 3901 | do {
|
| 3902 | struct page *page;
|
| 3903 | unsigned long offset;
|
| 3904 | unsigned long bytes;
|
| 3905 | size_t copied;
|
| 3906 | void *fsdata = NULL;
|
| 3907 |
|
| 3908 | offset = (pos & (PAGE_SIZE - 1));
|
| 3909 | bytes = min_t(unsigned long, PAGE_SIZE - offset,
|
| 3910 | iov_iter_count(i));
|
| 3911 |
|
| 3912 | again:
|
| 3913 | |
| 3914 | * Bring in the user page that we will copy from _first_.
|
| 3915 | * Otherwise there's a nasty deadlock on copying from the
|
| 3916 | * same page as we're writing to, without it being marked
|
| 3917 | * up-to-date.
|
| 3918 |
|
| 3919 | if (unlikely(fault_in_iov_iter_readable(i, bytes) == bytes)) {
|
| 3920 | status = -EFAULT;
|
| 3921 | break;
|
| 3922 | }
|
| 3923 |
|
| 3924 | if (fatal_signal_pending(current)) {
|
| 3925 | status = -EINTR;
|
| 3926 | break;
|
| 3927 | }
|
| 3928 |
|
| 3929 | status = a_ops->write_begin(file, mapping, pos, bytes,
|
| 3930 | &page, &fsdata);
|
| 3931 | if (unlikely(status < 0))
|
| 3932 | break;
|
| 3933 |
|
| 3934 | if (mapping_writably_mapped(mapping))
|
| 3935 | flush_dcache_page(page);
|
| 3936 |
|
| 3937 | copied = copy_page_from_iter_atomic(page, offset, bytes, i);
|
| 3938 | flush_dcache_page(page);
|
| 3939 |
|
| 3940 | status = a_ops->write_end(file, mapping, pos, bytes, copied,
|
| 3941 | page, fsdata);
|
| 3942 | if (unlikely(status != copied)) {
|
| 3943 | iov_iter_revert(i, copied - max(status, 0L));
|
| 3944 | if (unlikely(status < 0))
|
| 3945 | break;
|
| 3946 | }
|
| 3947 | cond_resched();
|
| 3948 |
|
| 3949 | if (unlikely(status == 0)) {
|
| 3950 | |
| 3951 | * A short copy made ->write_end() reject the
|
| 3952 | * thing entirely. Might be memory poisoning
|
| 3953 | * halfway through, might be a race with munmap,
|
| 3954 | * might be severe memory pressure.
|
| 3955 |
|
| 3956 | if (copied)
|
| 3957 | bytes = copied;
|
| 3958 | goto again;
|
| 3959 | }
|
| 3960 | pos += status;
|
| 3961 | written += status;
|
| 3962 |
|
| 3963 | balance_dirty_pages_ratelimited(mapping);
|
| 3964 | } while (iov_iter_count(i));
|
| 3965 |
|
| 3966 | return written ? written : status;
|
| 3967 | }
|
| 3968 | EXPORT_SYMBOL(generic_perform_write);
|
| 3969 |
|
| 3970 | |
| 3971 | * __generic_file_write_iter - write data to a file
|
| 3972 | * @iocb: IO state structure (file, offset, etc.)
|
| 3973 | * @from: iov_iter with data to write
|
| 3974 | *
|
| 3975 | * This function does all the work needed for actually writing data to a
|
| 3976 | * file. It does all basic checks, removes SUID from the file, updates
|
| 3977 | * modification times and calls proper subroutines depending on whether we
|
| 3978 | * do direct IO or a standard buffered write.
|
| 3979 | *
|
| 3980 | * It expects i_rwsem to be grabbed unless we work on a block device or similar
|
| 3981 | * object which does not need locking at all.
|
| 3982 | *
|
| 3983 | * This function does *not* take care of syncing data in case of O_SYNC write.
|
| 3984 | * A caller has to handle it. This is mainly due to the fact that we want to
|
| 3985 | * avoid syncing under i_rwsem.
|
| 3986 | *
|
| 3987 | * Return:
|
| 3988 | * * number of bytes written, even for truncated writes
|
| 3989 | * * negative error code if no data has been written at all
|
| 3990 |
|
| 3991 | ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
|
| 3992 | {
|
| 3993 | struct file *file = iocb->ki_filp;
|
| 3994 | struct address_space *mapping = file->f_mapping;
|
| 3995 | struct inode *inode = mapping->host;
|
| 3996 | ssize_t written = 0;
|
| 3997 | ssize_t err;
|
| 3998 | ssize_t status;
|
| 3999 |
|
| 4000 |
|
| 4001 | current->backing_dev_info = inode_to_bdi(inode);
|
| 4002 | err = file_remove_privs(file);
|
| 4003 | if (err)
|
| 4004 | goto out;
|
| 4005 |
|
| 4006 | err = file_update_time(file);
|
| 4007 | if (err)
|
| 4008 | goto out;
|
| 4009 |
|
| 4010 | if (iocb->ki_flags & IOCB_DIRECT) {
|
| 4011 | loff_t pos, endbyte;
|
| 4012 |
|
| 4013 | written = generic_file_direct_write(iocb, from);
|
| 4014 | |
| 4015 | * If the write stopped short of completing, fall back to
|
| 4016 | * buffered writes. Some filesystems do this for writes to
|
| 4017 | * holes, for example. For DAX files, a buffered write will
|
| 4018 | * not succeed (even if it did, DAX does not handle dirty
|
| 4019 | * page-cache pages correctly).
|
| 4020 |
|
| 4021 | if (written < 0 || !iov_iter_count(from) || IS_DAX(inode))
|
| 4022 | goto out;
|
| 4023 |
|
| 4024 | pos = iocb->ki_pos;
|
| 4025 | status = generic_perform_write(iocb, from);
|
| 4026 | |
| 4027 | * If generic_perform_write() returned a synchronous error
|
| 4028 | * then we want to return the number of bytes which were
|
| 4029 | * direct-written, or the error code if that was zero. Note
|
| 4030 | * that this differs from normal direct-io semantics, which
|
| 4031 | * will return -EFOO even if some bytes were written.
|
| 4032 |
|
| 4033 | if (unlikely(status < 0)) {
|
| 4034 | err = status;
|
| 4035 | goto out;
|
| 4036 | }
|
| 4037 | |
| 4038 | * We need to ensure that the page cache pages are written to
|
| 4039 | * disk and invalidated to preserve the expected O_DIRECT
|
| 4040 | * semantics.
|
| 4041 |
|
| 4042 | endbyte = pos + status - 1;
|
| 4043 | err = filemap_write_and_wait_range(mapping, pos, endbyte);
|
| 4044 | if (err == 0) {
|
| 4045 | iocb->ki_pos = endbyte + 1;
|
| 4046 | written += status;
|
| 4047 | invalidate_mapping_pages(mapping,
|
| 4048 | pos >> PAGE_SHIFT,
|
| 4049 | endbyte >> PAGE_SHIFT);
|
| 4050 | } else {
|
| 4051 | |
| 4052 | * We don't know how much we wrote, so just return
|
| 4053 | * the number of bytes which were direct-written
|
| 4054 |
|
| 4055 | }
|
| 4056 | } else {
|
| 4057 | written = generic_perform_write(iocb, from);
|
| 4058 | if (likely(written > 0))
|
| 4059 | iocb->ki_pos += written;
|
| 4060 | }
|
| 4061 | out:
|
| 4062 | current->backing_dev_info = NULL;
|
| 4063 | return written ? written : err;
|
| 4064 | }
|
| 4065 | EXPORT_SYMBOL(__generic_file_write_iter);
|
| 4066 |
|
| 4067 | |
| 4068 | * generic_file_write_iter - write data to a file
|
| 4069 | * @iocb: IO state structure
|
| 4070 | * @from: iov_iter with data to write
|
| 4071 | *
|
| 4072 | * This is a wrapper around __generic_file_write_iter() to be used by most
|
| 4073 | * filesystems. It takes care of syncing the file in case of O_SYNC file
|
| 4074 | * and acquires i_rwsem as needed.
|
| 4075 | * Return:
|
| 4076 | * * negative error code if no data has been written at all of
|
| 4077 | * vfs_fsync_range() failed for a synchronous write
|
| 4078 | * * number of bytes written, even for truncated writes
|
| 4079 |
|
| 4080 | ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
|
| 4081 | {
|
| 4082 | struct file *file = iocb->ki_filp;
|
| 4083 | struct inode *inode = file->f_mapping->host;
|
| 4084 | ssize_t ret;
|
| 4085 |
|
| 4086 | inode_lock(inode);
|
| 4087 | ret = generic_write_checks(iocb, from);
|
| 4088 | if (ret > 0)
|
| 4089 | ret = __generic_file_write_iter(iocb, from);
|
| 4090 | inode_unlock(inode);
|
| 4091 |
|
| 4092 | if (ret > 0)
|
| 4093 | ret = generic_write_sync(iocb, ret);
|
| 4094 | return ret;
|
| 4095 | }
|
| 4096 | EXPORT_SYMBOL(generic_file_write_iter);
|
| 4097 |
|
| 4098 | |
| 4099 | * filemap_release_folio() - Release fs-specific metadata on a folio.
|
| 4100 | * @folio: The folio which the kernel is trying to free.
|
| 4101 | * @gfp: Memory allocation flags (and I/O mode).
|
| 4102 | *
|
| 4103 | * The address_space is trying to release any data attached to a folio
|
| 4104 | * (presumably at folio->private).
|
| 4105 | *
|
| 4106 | * This will also be called if the private_2 flag is set on a page,
|
| 4107 | * indicating that the folio has other metadata associated with it.
|
| 4108 | *
|
| 4109 | * The @gfp argument specifies whether I/O may be performed to release
|
| 4110 | * this page (__GFP_IO), and whether the call may block
|
| 4111 | * (__GFP_RECLAIM & __GFP_FS).
|
| 4112 | *
|
| 4113 | * Return: %true if the release was successful, otherwise %false.
|
| 4114 |
|
| 4115 | bool filemap_release_folio(struct folio *folio, gfp_t gfp)
|
| 4116 | {
|
| 4117 | struct address_space * const mapping = folio->mapping;
|
| 4118 |
|
| 4119 | BUG_ON(!folio_test_locked(folio));
|
| 4120 | if (folio_test_writeback(folio))
|
| 4121 | return false;
|
| 4122 |
|
| 4123 | if (mapping && mapping->a_ops->release_folio)
|
| 4124 | return mapping->a_ops->release_folio(folio, gfp);
|
| 4125 | return try_to_free_buffers(folio);
|
| 4126 | }
|
| 4127 | EXPORT_SYMBOL(filemap_release_folio);
|