| 1 | |
| 2 | * linux/mm/filemap.c
|
| 3 | *
|
| 4 | * Copyright (C) 1994-1999 Linus Torvalds
|
| 5 |
|
| 6 |
|
| 7 | |
| 8 | * This file handles the generic file mmap semantics used by
|
| 9 | * most "normal" filesystems (but you don't /have/ to use this:
|
| 10 | * the NFS filesystem used to do this differently, for example)
|
| 11 |
|
| 12 | #include <linux/export.h>
|
| 13 | #include <linux/compiler.h>
|
| 14 | #include <linux/dax.h>
|
| 15 | #include <linux/fs.h>
|
| 16 | #include <linux/uaccess.h>
|
| 17 | #include <linux/capability.h>
|
| 18 | #include <linux/kernel_stat.h>
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| 19 | #include <linux/gfp.h>
|
| 20 | #include <linux/mm.h>
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| 21 | #include <linux/swap.h>
|
| 22 | #include <linux/mman.h>
|
| 23 | #include <linux/pagemap.h>
|
| 24 | #include <linux/file.h>
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| 25 | #include <linux/uio.h>
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| 26 | #include <linux/hash.h>
|
| 27 | #include <linux/writeback.h>
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| 28 | #include <linux/backing-dev.h>
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| 29 | #include <linux/pagevec.h>
|
| 30 | #include <linux/blkdev.h>
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| 31 | #include <linux/security.h>
|
| 32 | #include <linux/cpuset.h>
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| 33 | #include <linux/hardirq.h>
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| 34 | #include <linux/hugetlb.h>
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| 35 | #include <linux/memcontrol.h>
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| 36 | #include <linux/cleancache.h>
|
| 37 | #include <linux/rmap.h>
|
| 38 | #include "internal.h"
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| 39 |
|
| 40 | #define CREATE_TRACE_POINTS
|
| 41 | #include <trace/events/filemap.h>
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| 42 |
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| 43 | |
| 44 | * FIXME: remove all knowledge of the buffer layer from the core VM
|
| 45 |
|
| 46 | #include <linux/buffer_head.h>
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| 47 |
|
| 48 | #include <asm/mman.h>
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| 49 |
|
| 50 | |
| 51 | * Shared mappings implemented 30.11.1994. It's not fully working yet,
|
| 52 | * though.
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| 53 | *
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| 54 | * Shared mappings now work. 15.8.1995 Bruno.
|
| 55 | *
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| 56 | * finished 'unifying' the page and buffer cache and SMP-threaded the
|
| 57 | * page-cache, 21.05.1999, Ingo Molnar <[email protected]>
|
| 58 | *
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| 59 | * SMP-threaded pagemap-LRU 1999, Andrea Arcangeli <[email protected]>
|
| 60 |
|
| 61 |
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| 62 | |
| 63 | * Lock ordering:
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| 64 | *
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| 65 | * ->i_mmap_rwsem (truncate_pagecache)
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| 66 | * ->private_lock (__free_pte->__set_page_dirty_buffers)
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| 67 | * ->swap_lock (exclusive_swap_page, others)
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| 68 | * ->mapping->tree_lock
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| 69 | *
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| 70 | * ->i_mutex
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| 71 | * ->i_mmap_rwsem (truncate->unmap_mapping_range)
|
| 72 | *
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| 73 | * ->mmap_sem
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| 74 | * ->i_mmap_rwsem
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| 75 | * ->page_table_lock or pte_lock (various, mainly in memory.c)
|
| 76 | * ->mapping->tree_lock (arch-dependent flush_dcache_mmap_lock)
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| 77 | *
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| 78 | * ->mmap_sem
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| 79 | * ->lock_page (access_process_vm)
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| 80 | *
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| 81 | * ->i_mutex (generic_perform_write)
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| 82 | * ->mmap_sem (fault_in_pages_readable->do_page_fault)
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| 83 | *
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| 84 | * bdi->wb.list_lock
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| 85 | * sb_lock (fs/fs-writeback.c)
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| 86 | * ->mapping->tree_lock (__sync_single_inode)
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| 87 | *
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| 88 | * ->i_mmap_rwsem
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| 89 | * ->anon_vma.lock (vma_adjust)
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| 90 | *
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| 91 | * ->anon_vma.lock
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| 92 | * ->page_table_lock or pte_lock (anon_vma_prepare and various)
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| 93 | *
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| 94 | * ->page_table_lock or pte_lock
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| 95 | * ->swap_lock (try_to_unmap_one)
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| 96 | * ->private_lock (try_to_unmap_one)
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| 97 | * ->tree_lock (try_to_unmap_one)
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| 98 | * ->zone.lru_lock (follow_page->mark_page_accessed)
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| 99 | * ->zone.lru_lock (check_pte_range->isolate_lru_page)
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| 100 | * ->private_lock (page_remove_rmap->set_page_dirty)
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| 101 | * ->tree_lock (page_remove_rmap->set_page_dirty)
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| 102 | * bdi.wb->list_lock (page_remove_rmap->set_page_dirty)
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| 103 | * ->inode->i_lock (page_remove_rmap->set_page_dirty)
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| 104 | * ->memcg->move_lock (page_remove_rmap->lock_page_memcg)
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| 105 | * bdi.wb->list_lock (zap_pte_range->set_page_dirty)
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| 106 | * ->inode->i_lock (zap_pte_range->set_page_dirty)
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| 107 | * ->private_lock (zap_pte_range->__set_page_dirty_buffers)
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| 108 | *
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| 109 | * ->i_mmap_rwsem
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| 110 | * ->tasklist_lock (memory_failure, collect_procs_ao)
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| 111 |
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| 112 |
|
| 113 | static void page_cache_tree_delete(struct address_space *mapping,
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| 114 | struct page *page, void *shadow)
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| 115 | {
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| 116 | struct radix_tree_node *node;
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| 117 | unsigned long index;
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| 118 | unsigned int offset;
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| 119 | unsigned int tag;
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| 120 | void **slot;
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| 121 |
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| 122 | VM_BUG_ON(!PageLocked(page));
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| 123 |
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| 124 | __radix_tree_lookup(&mapping->page_tree, page->index, &node, &slot);
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| 125 |
|
| 126 | if (shadow) {
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| 127 | mapping->nrexceptional++;
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| 128 | |
| 129 | * Make sure the nrexceptional update is committed before
|
| 130 | * the nrpages update so that final truncate racing
|
| 131 | * with reclaim does not see both counters 0 at the
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| 132 | * same time and miss a shadow entry.
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| 133 |
|
| 134 | smp_wmb();
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| 135 | }
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| 136 | mapping->nrpages--;
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| 137 |
|
| 138 | if (!node) {
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| 139 |
|
| 140 | mapping->page_tree.gfp_mask &= __GFP_BITS_MASK;
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| 141 | radix_tree_replace_slot(slot, shadow);
|
| 142 | return;
|
| 143 | }
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| 144 |
|
| 145 |
|
| 146 | index = page->index;
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| 147 | offset = index & RADIX_TREE_MAP_MASK;
|
| 148 | for (tag = 0; tag < RADIX_TREE_MAX_TAGS; tag++) {
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| 149 | if (test_bit(offset, node->tags[tag]))
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| 150 | radix_tree_tag_clear(&mapping->page_tree, index, tag);
|
| 151 | }
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| 152 |
|
| 153 |
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| 154 | radix_tree_replace_slot(slot, shadow);
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| 155 | workingset_node_pages_dec(node);
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| 156 | if (shadow)
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| 157 | workingset_node_shadows_inc(node);
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| 158 | else
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| 159 | if (__radix_tree_delete_node(&mapping->page_tree, node))
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| 160 | return;
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| 161 |
|
| 162 | |
| 163 | * Track node that only contains shadow entries.
|
| 164 | *
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| 165 | * Avoid acquiring the list_lru lock if already tracked. The
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| 166 | * list_empty() test is safe as node->private_list is
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| 167 | * protected by mapping->tree_lock.
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| 168 |
|
| 169 | if (!workingset_node_pages(node) &&
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| 170 | list_empty(&node->private_list)) {
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| 171 | node->private_data = mapping;
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| 172 | list_lru_add(&workingset_shadow_nodes, &node->private_list);
|
| 173 | }
|
| 174 | }
|
| 175 |
|
| 176 | |
| 177 | * Delete a page from the page cache and free it. Caller has to make
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| 178 | * sure the page is locked and that nobody else uses it - or that usage
|
| 179 | * is safe. The caller must hold the mapping's tree_lock.
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| 180 |
|
| 181 | void __delete_from_page_cache(struct page *page, void *shadow)
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| 182 | {
|
| 183 | struct address_space *mapping = page->mapping;
|
| 184 |
|
| 185 | trace_mm_filemap_delete_from_page_cache(page);
|
| 186 | |
| 187 | * if we're uptodate, flush out into the cleancache, otherwise
|
| 188 | * invalidate any existing cleancache entries. We can't leave
|
| 189 | * stale data around in the cleancache once our page is gone
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| 190 |
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| 191 | if (PageUptodate(page) && PageMappedToDisk(page))
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| 192 | cleancache_put_page(page);
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| 193 | else
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| 194 | cleancache_invalidate_page(mapping, page);
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| 195 |
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| 196 | VM_BUG_ON_PAGE(page_mapped(page), page);
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| 197 | if (!IS_ENABLED(CONFIG_DEBUG_VM) && unlikely(page_mapped(page))) {
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| 198 | int mapcount;
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| 199 |
|
| 200 | pr_alert("BUG: Bad page cache in process %s pfn:%05lx\n",
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| 201 | current->comm, page_to_pfn(page));
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| 202 | dump_page(page, "still mapped when deleted");
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| 203 | dump_stack();
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| 204 | add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
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| 205 |
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| 206 | mapcount = page_mapcount(page);
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| 207 | if (mapping_exiting(mapping) &&
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| 208 | page_count(page) >= mapcount + 2) {
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| 209 | |
| 210 | * All vmas have already been torn down, so it's
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| 211 | * a good bet that actually the page is unmapped,
|
| 212 | * and we'd prefer not to leak it: if we're wrong,
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| 213 | * some other bad page check should catch it later.
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| 214 |
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| 215 | page_mapcount_reset(page);
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| 216 | atomic_sub(mapcount, &page->_count);
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| 217 | }
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| 218 | }
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| 219 |
|
| 220 | page_cache_tree_delete(mapping, page, shadow);
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| 221 |
|
| 222 | page->mapping = NULL;
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| 223 |
|
| 224 |
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| 225 |
|
| 226 | if (!PageHuge(page))
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| 227 | __dec_zone_page_state(page, NR_FILE_PAGES);
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| 228 | if (PageSwapBacked(page))
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| 229 | __dec_zone_page_state(page, NR_SHMEM);
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| 230 |
|
| 231 | |
| 232 | * At this point page must be either written or cleaned by truncate.
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| 233 | * Dirty page here signals a bug and loss of unwritten data.
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| 234 | *
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| 235 | * This fixes dirty accounting after removing the page entirely but
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| 236 | * leaves PageDirty set: it has no effect for truncated page and
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| 237 | * anyway will be cleared before returning page into buddy allocator.
|
| 238 |
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| 239 | if (WARN_ON_ONCE(PageDirty(page)))
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| 240 | account_page_cleaned(page, mapping, inode_to_wb(mapping->host));
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| 241 | }
|
| 242 |
|
| 243 | |
| 244 | * delete_from_page_cache - delete page from page cache
|
| 245 | * @page: the page which the kernel is trying to remove from page cache
|
| 246 | *
|
| 247 | * This must be called only on pages that have been verified to be in the page
|
| 248 | * cache and locked. It will never put the page into the free list, the caller
|
| 249 | * has a reference on the page.
|
| 250 |
|
| 251 | void delete_from_page_cache(struct page *page)
|
| 252 | {
|
| 253 | struct address_space *mapping = page->mapping;
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| 254 | unsigned long flags;
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| 255 |
|
| 256 | void (*freepage)(struct page *);
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| 257 |
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| 258 | BUG_ON(!PageLocked(page));
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| 259 |
|
| 260 | freepage = mapping->a_ops->freepage;
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| 261 |
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| 262 | spin_lock_irqsave(&mapping->tree_lock, flags);
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| 263 | __delete_from_page_cache(page, NULL);
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| 264 | spin_unlock_irqrestore(&mapping->tree_lock, flags);
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| 265 |
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| 266 | if (freepage)
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| 267 | freepage(page);
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| 268 | put_page(page);
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| 269 | }
|
| 270 | EXPORT_SYMBOL(delete_from_page_cache);
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| 271 |
|
| 272 | static int filemap_check_errors(struct address_space *mapping)
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| 273 | {
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| 274 | int ret = 0;
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| 275 |
|
| 276 | if (test_bit(AS_ENOSPC, &mapping->flags) &&
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| 277 | test_and_clear_bit(AS_ENOSPC, &mapping->flags))
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| 278 | ret = -ENOSPC;
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| 279 | if (test_bit(AS_EIO, &mapping->flags) &&
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| 280 | test_and_clear_bit(AS_EIO, &mapping->flags))
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| 281 | ret = -EIO;
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| 282 | return ret;
|
| 283 | }
|
| 284 |
|
| 285 | |
| 286 | * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
|
| 287 | * @mapping: address space structure to write
|
| 288 | * @start: offset in bytes where the range starts
|
| 289 | * @end: offset in bytes where the range ends (inclusive)
|
| 290 | * @sync_mode: enable synchronous operation
|
| 291 | *
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| 292 | * Start writeback against all of a mapping's dirty pages that lie
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| 293 | * within the byte offsets <start, end> inclusive.
|
| 294 | *
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| 295 | * If sync_mode is WB_SYNC_ALL then this is a "data integrity" operation, as
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| 296 | * opposed to a regular memory cleansing writeback. The difference between
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| 297 | * these two operations is that if a dirty page/buffer is encountered, it must
|
| 298 | * be waited upon, and not just skipped over.
|
| 299 |
|
| 300 | int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
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| 301 | loff_t end, int sync_mode)
|
| 302 | {
|
| 303 | int ret;
|
| 304 | struct writeback_control wbc = {
|
| 305 | .sync_mode = sync_mode,
|
| 306 | .nr_to_write = LONG_MAX,
|
| 307 | .range_start = start,
|
| 308 | .range_end = end,
|
| 309 | };
|
| 310 |
|
| 311 | if (!mapping_cap_writeback_dirty(mapping))
|
| 312 | return 0;
|
| 313 |
|
| 314 | wbc_attach_fdatawrite_inode(&wbc, mapping->host);
|
| 315 | ret = do_writepages(mapping, &wbc);
|
| 316 | wbc_detach_inode(&wbc);
|
| 317 | return ret;
|
| 318 | }
|
| 319 |
|
| 320 | static inline int __filemap_fdatawrite(struct address_space *mapping,
|
| 321 | int sync_mode)
|
| 322 | {
|
| 323 | return __filemap_fdatawrite_range(mapping, 0, LLONG_MAX, sync_mode);
|
| 324 | }
|
| 325 |
|
| 326 | int filemap_fdatawrite(struct address_space *mapping)
|
| 327 | {
|
| 328 | return __filemap_fdatawrite(mapping, WB_SYNC_ALL);
|
| 329 | }
|
| 330 | EXPORT_SYMBOL(filemap_fdatawrite);
|
| 331 |
|
| 332 | int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
|
| 333 | loff_t end)
|
| 334 | {
|
| 335 | return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
|
| 336 | }
|
| 337 | EXPORT_SYMBOL(filemap_fdatawrite_range);
|
| 338 |
|
| 339 | |
| 340 | * filemap_flush - mostly a non-blocking flush
|
| 341 | * @mapping: target address_space
|
| 342 | *
|
| 343 | * This is a mostly non-blocking flush. Not suitable for data-integrity
|
| 344 | * purposes - I/O may not be started against all dirty pages.
|
| 345 |
|
| 346 | int filemap_flush(struct address_space *mapping)
|
| 347 | {
|
| 348 | return __filemap_fdatawrite(mapping, WB_SYNC_NONE);
|
| 349 | }
|
| 350 | EXPORT_SYMBOL(filemap_flush);
|
| 351 |
|
| 352 | static int __filemap_fdatawait_range(struct address_space *mapping,
|
| 353 | loff_t start_byte, loff_t end_byte)
|
| 354 | {
|
| 355 | pgoff_t index = start_byte >> PAGE_SHIFT;
|
| 356 | pgoff_t end = end_byte >> PAGE_SHIFT;
|
| 357 | struct pagevec pvec;
|
| 358 | int nr_pages;
|
| 359 | int ret = 0;
|
| 360 |
|
| 361 | if (end_byte < start_byte)
|
| 362 | goto out;
|
| 363 |
|
| 364 | pagevec_init(&pvec, 0);
|
| 365 | while ((index <= end) &&
|
| 366 | (nr_pages = pagevec_lookup_tag(&pvec, mapping, &index,
|
| 367 | PAGECACHE_TAG_WRITEBACK,
|
| 368 | min(end - index, (pgoff_t)PAGEVEC_SIZE-1) + 1)) != 0) {
|
| 369 | unsigned i;
|
| 370 |
|
| 371 | for (i = 0; i < nr_pages; i++) {
|
| 372 | struct page *page = pvec.pages[i];
|
| 373 |
|
| 374 |
|
| 375 | if (page->index > end)
|
| 376 | continue;
|
| 377 |
|
| 378 | wait_on_page_writeback(page);
|
| 379 | if (TestClearPageError(page))
|
| 380 | ret = -EIO;
|
| 381 | }
|
| 382 | pagevec_release(&pvec);
|
| 383 | cond_resched();
|
| 384 | }
|
| 385 | out:
|
| 386 | return ret;
|
| 387 | }
|
| 388 |
|
| 389 | |
| 390 | * filemap_fdatawait_range - wait for writeback to complete
|
| 391 | * @mapping: address space structure to wait for
|
| 392 | * @start_byte: offset in bytes where the range starts
|
| 393 | * @end_byte: offset in bytes where the range ends (inclusive)
|
| 394 | *
|
| 395 | * Walk the list of under-writeback pages of the given address space
|
| 396 | * in the given range and wait for all of them. Check error status of
|
| 397 | * the address space and return it.
|
| 398 | *
|
| 399 | * Since the error status of the address space is cleared by this function,
|
| 400 | * callers are responsible for checking the return value and handling and/or
|
| 401 | * reporting the error.
|
| 402 |
|
| 403 | int filemap_fdatawait_range(struct address_space *mapping, loff_t start_byte,
|
| 404 | loff_t end_byte)
|
| 405 | {
|
| 406 | int ret, ret2;
|
| 407 |
|
| 408 | ret = __filemap_fdatawait_range(mapping, start_byte, end_byte);
|
| 409 | ret2 = filemap_check_errors(mapping);
|
| 410 | if (!ret)
|
| 411 | ret = ret2;
|
| 412 |
|
| 413 | return ret;
|
| 414 | }
|
| 415 | EXPORT_SYMBOL(filemap_fdatawait_range);
|
| 416 |
|
| 417 | |
| 418 | * filemap_fdatawait_keep_errors - wait for writeback without clearing errors
|
| 419 | * @mapping: address space structure to wait for
|
| 420 | *
|
| 421 | * Walk the list of under-writeback pages of the given address space
|
| 422 | * and wait for all of them. Unlike filemap_fdatawait(), this function
|
| 423 | * does not clear error status of the address space.
|
| 424 | *
|
| 425 | * Use this function if callers don't handle errors themselves. Expected
|
| 426 | * call sites are system-wide / filesystem-wide data flushers: e.g. sync(2),
|
| 427 | * fsfreeze(8)
|
| 428 |
|
| 429 | void filemap_fdatawait_keep_errors(struct address_space *mapping)
|
| 430 | {
|
| 431 | loff_t i_size = i_size_read(mapping->host);
|
| 432 |
|
| 433 | if (i_size == 0)
|
| 434 | return;
|
| 435 |
|
| 436 | __filemap_fdatawait_range(mapping, 0, i_size - 1);
|
| 437 | }
|
| 438 |
|
| 439 | |
| 440 | * filemap_fdatawait - wait for all under-writeback pages to complete
|
| 441 | * @mapping: address space structure to wait for
|
| 442 | *
|
| 443 | * Walk the list of under-writeback pages of the given address space
|
| 444 | * and wait for all of them. Check error status of the address space
|
| 445 | * and return it.
|
| 446 | *
|
| 447 | * Since the error status of the address space is cleared by this function,
|
| 448 | * callers are responsible for checking the return value and handling and/or
|
| 449 | * reporting the error.
|
| 450 |
|
| 451 | int filemap_fdatawait(struct address_space *mapping)
|
| 452 | {
|
| 453 | loff_t i_size = i_size_read(mapping->host);
|
| 454 |
|
| 455 | if (i_size == 0)
|
| 456 | return 0;
|
| 457 |
|
| 458 | return filemap_fdatawait_range(mapping, 0, i_size - 1);
|
| 459 | }
|
| 460 | EXPORT_SYMBOL(filemap_fdatawait);
|
| 461 |
|
| 462 | int filemap_write_and_wait(struct address_space *mapping)
|
| 463 | {
|
| 464 | int err = 0;
|
| 465 |
|
| 466 | if ((!dax_mapping(mapping) && mapping->nrpages) ||
|
| 467 | (dax_mapping(mapping) && mapping->nrexceptional)) {
|
| 468 | err = filemap_fdatawrite(mapping);
|
| 469 | |
| 470 | * Even if the above returned error, the pages may be
|
| 471 | * written partially (e.g. -ENOSPC), so we wait for it.
|
| 472 | * But the -EIO is special case, it may indicate the worst
|
| 473 | * thing (e.g. bug) happened, so we avoid waiting for it.
|
| 474 |
|
| 475 | if (err != -EIO) {
|
| 476 | int err2 = filemap_fdatawait(mapping);
|
| 477 | if (!err)
|
| 478 | err = err2;
|
| 479 | }
|
| 480 | } else {
|
| 481 | err = filemap_check_errors(mapping);
|
| 482 | }
|
| 483 | return err;
|
| 484 | }
|
| 485 | EXPORT_SYMBOL(filemap_write_and_wait);
|
| 486 |
|
| 487 | |
| 488 | * filemap_write_and_wait_range - write out & wait on a file range
|
| 489 | * @mapping: the address_space for the pages
|
| 490 | * @lstart: offset in bytes where the range starts
|
| 491 | * @lend: offset in bytes where the range ends (inclusive)
|
| 492 | *
|
| 493 | * Write out and wait upon file offsets lstart->lend, inclusive.
|
| 494 | *
|
| 495 | * Note that `lend' is inclusive (describes the last byte to be written) so
|
| 496 | * that this function can be used to write to the very end-of-file (end = -1).
|
| 497 |
|
| 498 | int filemap_write_and_wait_range(struct address_space *mapping,
|
| 499 | loff_t lstart, loff_t lend)
|
| 500 | {
|
| 501 | int err = 0;
|
| 502 |
|
| 503 | if ((!dax_mapping(mapping) && mapping->nrpages) ||
|
| 504 | (dax_mapping(mapping) && mapping->nrexceptional)) {
|
| 505 | err = __filemap_fdatawrite_range(mapping, lstart, lend,
|
| 506 | WB_SYNC_ALL);
|
| 507 |
|
| 508 | if (err != -EIO) {
|
| 509 | int err2 = filemap_fdatawait_range(mapping,
|
| 510 | lstart, lend);
|
| 511 | if (!err)
|
| 512 | err = err2;
|
| 513 | }
|
| 514 | } else {
|
| 515 | err = filemap_check_errors(mapping);
|
| 516 | }
|
| 517 | return err;
|
| 518 | }
|
| 519 | EXPORT_SYMBOL(filemap_write_and_wait_range);
|
| 520 |
|
| 521 | |
| 522 | * replace_page_cache_page - replace a pagecache page with a new one
|
| 523 | * @old: page to be replaced
|
| 524 | * @new: page to replace with
|
| 525 | * @gfp_mask: allocation mode
|
| 526 | *
|
| 527 | * This function replaces a page in the pagecache with a new one. On
|
| 528 | * success it acquires the pagecache reference for the new page and
|
| 529 | * drops it for the old page. Both the old and new pages must be
|
| 530 | * locked. This function does not add the new page to the LRU, the
|
| 531 | * caller must do that.
|
| 532 | *
|
| 533 | * The remove + add is atomic. The only way this function can fail is
|
| 534 | * memory allocation failure.
|
| 535 |
|
| 536 | int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
|
| 537 | {
|
| 538 | int error;
|
| 539 |
|
| 540 | VM_BUG_ON_PAGE(!PageLocked(old), old);
|
| 541 | VM_BUG_ON_PAGE(!PageLocked(new), new);
|
| 542 | VM_BUG_ON_PAGE(new->mapping, new);
|
| 543 |
|
| 544 | error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
|
| 545 | if (!error) {
|
| 546 | struct address_space *mapping = old->mapping;
|
| 547 | void (*freepage)(struct page *);
|
| 548 | unsigned long flags;
|
| 549 |
|
| 550 | pgoff_t offset = old->index;
|
| 551 | freepage = mapping->a_ops->freepage;
|
| 552 |
|
| 553 | get_page(new);
|
| 554 | new->mapping = mapping;
|
| 555 | new->index = offset;
|
| 556 |
|
| 557 | spin_lock_irqsave(&mapping->tree_lock, flags);
|
| 558 | __delete_from_page_cache(old, NULL);
|
| 559 | error = radix_tree_insert(&mapping->page_tree, offset, new);
|
| 560 | BUG_ON(error);
|
| 561 | mapping->nrpages++;
|
| 562 |
|
| 563 | |
| 564 | * hugetlb pages do not participate in page cache accounting.
|
| 565 |
|
| 566 | if (!PageHuge(new))
|
| 567 | __inc_zone_page_state(new, NR_FILE_PAGES);
|
| 568 | if (PageSwapBacked(new))
|
| 569 | __inc_zone_page_state(new, NR_SHMEM);
|
| 570 | spin_unlock_irqrestore(&mapping->tree_lock, flags);
|
| 571 | mem_cgroup_migrate(old, new);
|
| 572 | radix_tree_preload_end();
|
| 573 | if (freepage)
|
| 574 | freepage(old);
|
| 575 | put_page(old);
|
| 576 | }
|
| 577 |
|
| 578 | return error;
|
| 579 | }
|
| 580 | EXPORT_SYMBOL_GPL(replace_page_cache_page);
|
| 581 |
|
| 582 | static int page_cache_tree_insert(struct address_space *mapping,
|
| 583 | struct page *page, void **shadowp)
|
| 584 | {
|
| 585 | struct radix_tree_node *node;
|
| 586 | void **slot;
|
| 587 | int error;
|
| 588 |
|
| 589 | error = __radix_tree_create(&mapping->page_tree, page->index, 0,
|
| 590 | &node, &slot);
|
| 591 | if (error)
|
| 592 | return error;
|
| 593 | if (*slot) {
|
| 594 | void *p;
|
| 595 |
|
| 596 | p = radix_tree_deref_slot_protected(slot, &mapping->tree_lock);
|
| 597 | if (!radix_tree_exceptional_entry(p))
|
| 598 | return -EEXIST;
|
| 599 |
|
| 600 | if (WARN_ON(dax_mapping(mapping)))
|
| 601 | return -EINVAL;
|
| 602 |
|
| 603 | if (shadowp)
|
| 604 | *shadowp = p;
|
| 605 | mapping->nrexceptional--;
|
| 606 | if (node)
|
| 607 | workingset_node_shadows_dec(node);
|
| 608 | }
|
| 609 | radix_tree_replace_slot(slot, page);
|
| 610 | mapping->nrpages++;
|
| 611 | if (node) {
|
| 612 | workingset_node_pages_inc(node);
|
| 613 | |
| 614 | * Don't track node that contains actual pages.
|
| 615 | *
|
| 616 | * Avoid acquiring the list_lru lock if already
|
| 617 | * untracked. The list_empty() test is safe as
|
| 618 | * node->private_list is protected by
|
| 619 | * mapping->tree_lock.
|
| 620 |
|
| 621 | if (!list_empty(&node->private_list))
|
| 622 | list_lru_del(&workingset_shadow_nodes,
|
| 623 | &node->private_list);
|
| 624 | }
|
| 625 | return 0;
|
| 626 | }
|
| 627 |
|
| 628 | static int __add_to_page_cache_locked(struct page *page,
|
| 629 | struct address_space *mapping,
|
| 630 | pgoff_t offset, gfp_t gfp_mask,
|
| 631 | void **shadowp)
|
| 632 | {
|
| 633 | int huge = PageHuge(page);
|
| 634 | struct mem_cgroup *memcg;
|
| 635 | int error;
|
| 636 |
|
| 637 | VM_BUG_ON_PAGE(!PageLocked(page), page);
|
| 638 | VM_BUG_ON_PAGE(PageSwapBacked(page), page);
|
| 639 |
|
| 640 | if (!huge) {
|
| 641 | error = mem_cgroup_try_charge(page, current->mm,
|
| 642 | gfp_mask, &memcg, false);
|
| 643 | if (error)
|
| 644 | return error;
|
| 645 | }
|
| 646 |
|
| 647 | error = radix_tree_maybe_preload(gfp_mask & ~__GFP_HIGHMEM);
|
| 648 | if (error) {
|
| 649 | if (!huge)
|
| 650 | mem_cgroup_cancel_charge(page, memcg, false);
|
| 651 | return error;
|
| 652 | }
|
| 653 |
|
| 654 | get_page(page);
|
| 655 | page->mapping = mapping;
|
| 656 | page->index = offset;
|
| 657 |
|
| 658 | spin_lock_irq(&mapping->tree_lock);
|
| 659 | error = page_cache_tree_insert(mapping, page, shadowp);
|
| 660 | radix_tree_preload_end();
|
| 661 | if (unlikely(error))
|
| 662 | goto err_insert;
|
| 663 |
|
| 664 |
|
| 665 | if (!huge)
|
| 666 | __inc_zone_page_state(page, NR_FILE_PAGES);
|
| 667 | spin_unlock_irq(&mapping->tree_lock);
|
| 668 | if (!huge)
|
| 669 | mem_cgroup_commit_charge(page, memcg, false, false);
|
| 670 | trace_mm_filemap_add_to_page_cache(page);
|
| 671 | return 0;
|
| 672 | err_insert:
|
| 673 | page->mapping = NULL;
|
| 674 |
|
| 675 | spin_unlock_irq(&mapping->tree_lock);
|
| 676 | if (!huge)
|
| 677 | mem_cgroup_cancel_charge(page, memcg, false);
|
| 678 | put_page(page);
|
| 679 | return error;
|
| 680 | }
|
| 681 |
|
| 682 | |
| 683 | * add_to_page_cache_locked - add a locked page to the pagecache
|
| 684 | * @page: page to add
|
| 685 | * @mapping: the page's address_space
|
| 686 | * @offset: page index
|
| 687 | * @gfp_mask: page allocation mode
|
| 688 | *
|
| 689 | * This function is used to add a page to the pagecache. It must be locked.
|
| 690 | * This function does not add the page to the LRU. The caller must do that.
|
| 691 |
|
| 692 | int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
|
| 693 | pgoff_t offset, gfp_t gfp_mask)
|
| 694 | {
|
| 695 | return __add_to_page_cache_locked(page, mapping, offset,
|
| 696 | gfp_mask, NULL);
|
| 697 | }
|
| 698 | EXPORT_SYMBOL(add_to_page_cache_locked);
|
| 699 |
|
| 700 | int add_to_page_cache_lru(struct page *page, struct address_space *mapping,
|
| 701 | pgoff_t offset, gfp_t gfp_mask)
|
| 702 | {
|
| 703 | void *shadow = NULL;
|
| 704 | int ret;
|
| 705 |
|
| 706 | __SetPageLocked(page);
|
| 707 | ret = __add_to_page_cache_locked(page, mapping, offset,
|
| 708 | gfp_mask, &shadow);
|
| 709 | if (unlikely(ret))
|
| 710 | __ClearPageLocked(page);
|
| 711 | else {
|
| 712 | |
| 713 | * The page might have been evicted from cache only
|
| 714 | * recently, in which case it should be activated like
|
| 715 | * any other repeatedly accessed page.
|
| 716 |
|
| 717 | if (shadow && workingset_refault(shadow)) {
|
| 718 | SetPageActive(page);
|
| 719 | workingset_activation(page);
|
| 720 | } else
|
| 721 | ClearPageActive(page);
|
| 722 | lru_cache_add(page);
|
| 723 | }
|
| 724 | return ret;
|
| 725 | }
|
| 726 | EXPORT_SYMBOL_GPL(add_to_page_cache_lru);
|
| 727 |
|
| 728 | #ifdef CONFIG_NUMA
|
| 729 | struct page *__page_cache_alloc(gfp_t gfp)
|
| 730 | {
|
| 731 | int n;
|
| 732 | struct page *page;
|
| 733 |
|
| 734 | if (cpuset_do_page_mem_spread()) {
|
| 735 | unsigned int cpuset_mems_cookie;
|
| 736 | do {
|
| 737 | cpuset_mems_cookie = read_mems_allowed_begin();
|
| 738 | n = cpuset_mem_spread_node();
|
| 739 | page = __alloc_pages_node(n, gfp, 0);
|
| 740 | } while (!page && read_mems_allowed_retry(cpuset_mems_cookie));
|
| 741 |
|
| 742 | return page;
|
| 743 | }
|
| 744 | return alloc_pages(gfp, 0);
|
| 745 | }
|
| 746 | EXPORT_SYMBOL(__page_cache_alloc);
|
| 747 | #endif
|
| 748 |
|
| 749 | |
| 750 | * In order to wait for pages to become available there must be
|
| 751 | * waitqueues associated with pages. By using a hash table of
|
| 752 | * waitqueues where the bucket discipline is to maintain all
|
| 753 | * waiters on the same queue and wake all when any of the pages
|
| 754 | * become available, and for the woken contexts to check to be
|
| 755 | * sure the appropriate page became available, this saves space
|
| 756 | * at a cost of "thundering herd" phenomena during rare hash
|
| 757 | * collisions.
|
| 758 |
|
| 759 | wait_queue_head_t *page_waitqueue(struct page *page)
|
| 760 | {
|
| 761 | const struct zone *zone = page_zone(page);
|
| 762 |
|
| 763 | return &zone->wait_table[hash_ptr(page, zone->wait_table_bits)];
|
| 764 | }
|
| 765 | EXPORT_SYMBOL(page_waitqueue);
|
| 766 |
|
| 767 | void wait_on_page_bit(struct page *page, int bit_nr)
|
| 768 | {
|
| 769 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
|
| 770 |
|
| 771 | if (test_bit(bit_nr, &page->flags))
|
| 772 | __wait_on_bit(page_waitqueue(page), &wait, bit_wait_io,
|
| 773 | TASK_UNINTERRUPTIBLE);
|
| 774 | }
|
| 775 | EXPORT_SYMBOL(wait_on_page_bit);
|
| 776 |
|
| 777 | int wait_on_page_bit_killable(struct page *page, int bit_nr)
|
| 778 | {
|
| 779 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
|
| 780 |
|
| 781 | if (!test_bit(bit_nr, &page->flags))
|
| 782 | return 0;
|
| 783 |
|
| 784 | return __wait_on_bit(page_waitqueue(page), &wait,
|
| 785 | bit_wait_io, TASK_KILLABLE);
|
| 786 | }
|
| 787 |
|
| 788 | int wait_on_page_bit_killable_timeout(struct page *page,
|
| 789 | int bit_nr, unsigned long timeout)
|
| 790 | {
|
| 791 | DEFINE_WAIT_BIT(wait, &page->flags, bit_nr);
|
| 792 |
|
| 793 | wait.key.timeout = jiffies + timeout;
|
| 794 | if (!test_bit(bit_nr, &page->flags))
|
| 795 | return 0;
|
| 796 | return __wait_on_bit(page_waitqueue(page), &wait,
|
| 797 | bit_wait_io_timeout, TASK_KILLABLE);
|
| 798 | }
|
| 799 | EXPORT_SYMBOL_GPL(wait_on_page_bit_killable_timeout);
|
| 800 |
|
| 801 | |
| 802 | * add_page_wait_queue - Add an arbitrary waiter to a page's wait queue
|
| 803 | * @page: Page defining the wait queue of interest
|
| 804 | * @waiter: Waiter to add to the queue
|
| 805 | *
|
| 806 | * Add an arbitrary @waiter to the wait queue for the nominated @page.
|
| 807 |
|
| 808 | void add_page_wait_queue(struct page *page, wait_queue_t *waiter)
|
| 809 | {
|
| 810 | wait_queue_head_t *q = page_waitqueue(page);
|
| 811 | unsigned long flags;
|
| 812 |
|
| 813 | spin_lock_irqsave(&q->lock, flags);
|
| 814 | __add_wait_queue(q, waiter);
|
| 815 | spin_unlock_irqrestore(&q->lock, flags);
|
| 816 | }
|
| 817 | EXPORT_SYMBOL_GPL(add_page_wait_queue);
|
| 818 |
|
| 819 | |
| 820 | * unlock_page - unlock a locked page
|
| 821 | * @page: the page
|
| 822 | *
|
| 823 | * Unlocks the page and wakes up sleepers in ___wait_on_page_locked().
|
| 824 | * Also wakes sleepers in wait_on_page_writeback() because the wakeup
|
| 825 | * mechanism between PageLocked pages and PageWriteback pages is shared.
|
| 826 | * But that's OK - sleepers in wait_on_page_writeback() just go back to sleep.
|
| 827 | *
|
| 828 | * The mb is necessary to enforce ordering between the clear_bit and the read
|
| 829 | * of the waitqueue (to avoid SMP races with a parallel wait_on_page_locked()).
|
| 830 |
|
| 831 | void unlock_page(struct page *page)
|
| 832 | {
|
| 833 | page = compound_head(page);
|
| 834 | VM_BUG_ON_PAGE(!PageLocked(page), page);
|
| 835 | clear_bit_unlock(PG_locked, &page->flags);
|
| 836 | smp_mb__after_atomic();
|
| 837 | wake_up_page(page, PG_locked);
|
| 838 | }
|
| 839 | EXPORT_SYMBOL(unlock_page);
|
| 840 |
|
| 841 | |
| 842 | * end_page_writeback - end writeback against a page
|
| 843 | * @page: the page
|
| 844 |
|
| 845 | void end_page_writeback(struct page *page)
|
| 846 | {
|
| 847 | |
| 848 | * TestClearPageReclaim could be used here but it is an atomic
|
| 849 | * operation and overkill in this particular case. Failing to
|
| 850 | * shuffle a page marked for immediate reclaim is too mild to
|
| 851 | * justify taking an atomic operation penalty at the end of
|
| 852 | * ever page writeback.
|
| 853 |
|
| 854 | if (PageReclaim(page)) {
|
| 855 | ClearPageReclaim(page);
|
| 856 | rotate_reclaimable_page(page);
|
| 857 | }
|
| 858 |
|
| 859 | if (!test_clear_page_writeback(page))
|
| 860 | BUG();
|
| 861 |
|
| 862 | smp_mb__after_atomic();
|
| 863 | wake_up_page(page, PG_writeback);
|
| 864 | }
|
| 865 | EXPORT_SYMBOL(end_page_writeback);
|
| 866 |
|
| 867 | |
| 868 | * After completing I/O on a page, call this routine to update the page
|
| 869 | * flags appropriately
|
| 870 |
|
| 871 | void page_endio(struct page *page, int rw, int err)
|
| 872 | {
|
| 873 | if (rw == READ) {
|
| 874 | if (!err) {
|
| 875 | SetPageUptodate(page);
|
| 876 | } else {
|
| 877 | ClearPageUptodate(page);
|
| 878 | SetPageError(page);
|
| 879 | }
|
| 880 | unlock_page(page);
|
| 881 | } else {
|
| 882 | if (err) {
|
| 883 | SetPageError(page);
|
| 884 | if (page->mapping)
|
| 885 | mapping_set_error(page->mapping, err);
|
| 886 | }
|
| 887 | end_page_writeback(page);
|
| 888 | }
|
| 889 | }
|
| 890 | EXPORT_SYMBOL_GPL(page_endio);
|
| 891 |
|
| 892 | |
| 893 | * __lock_page - get a lock on the page, assuming we need to sleep to get it
|
| 894 | * @page: the page to lock
|
| 895 |
|
| 896 | void __lock_page(struct page *page)
|
| 897 | {
|
| 898 | struct page *page_head = compound_head(page);
|
| 899 | DEFINE_WAIT_BIT(wait, &page_head->flags, PG_locked);
|
| 900 |
|
| 901 | __wait_on_bit_lock(page_waitqueue(page_head), &wait, bit_wait_io,
|
| 902 | TASK_UNINTERRUPTIBLE);
|
| 903 | }
|
| 904 | EXPORT_SYMBOL(__lock_page);
|
| 905 |
|
| 906 | int __lock_page_killable(struct page *page)
|
| 907 | {
|
| 908 | struct page *page_head = compound_head(page);
|
| 909 | DEFINE_WAIT_BIT(wait, &page_head->flags, PG_locked);
|
| 910 |
|
| 911 | return __wait_on_bit_lock(page_waitqueue(page_head), &wait,
|
| 912 | bit_wait_io, TASK_KILLABLE);
|
| 913 | }
|
| 914 | EXPORT_SYMBOL_GPL(__lock_page_killable);
|
| 915 |
|
| 916 | |
| 917 | * Return values:
|
| 918 | * 1 - page is locked; mmap_sem is still held.
|
| 919 | * 0 - page is not locked.
|
| 920 | * mmap_sem has been released (up_read()), unless flags had both
|
| 921 | * FAULT_FLAG_ALLOW_RETRY and FAULT_FLAG_RETRY_NOWAIT set, in
|
| 922 | * which case mmap_sem is still held.
|
| 923 | *
|
| 924 | * If neither ALLOW_RETRY nor KILLABLE are set, will always return 1
|
| 925 | * with the page locked and the mmap_sem unperturbed.
|
| 926 |
|
| 927 | int __lock_page_or_retry(struct page *page, struct mm_struct *mm,
|
| 928 | unsigned int flags)
|
| 929 | {
|
| 930 | if (flags & FAULT_FLAG_ALLOW_RETRY) {
|
| 931 | |
| 932 | * CAUTION! In this case, mmap_sem is not released
|
| 933 | * even though return 0.
|
| 934 |
|
| 935 | if (flags & FAULT_FLAG_RETRY_NOWAIT)
|
| 936 | return 0;
|
| 937 |
|
| 938 | up_read(&mm->mmap_sem);
|
| 939 | if (flags & FAULT_FLAG_KILLABLE)
|
| 940 | wait_on_page_locked_killable(page);
|
| 941 | else
|
| 942 | wait_on_page_locked(page);
|
| 943 | return 0;
|
| 944 | } else {
|
| 945 | if (flags & FAULT_FLAG_KILLABLE) {
|
| 946 | int ret;
|
| 947 |
|
| 948 | ret = __lock_page_killable(page);
|
| 949 | if (ret) {
|
| 950 | up_read(&mm->mmap_sem);
|
| 951 | return 0;
|
| 952 | }
|
| 953 | } else
|
| 954 | __lock_page(page);
|
| 955 | return 1;
|
| 956 | }
|
| 957 | }
|
| 958 |
|
| 959 | |
| 960 | * page_cache_next_hole - find the next hole (not-present entry)
|
| 961 | * @mapping: mapping
|
| 962 | * @index: index
|
| 963 | * @max_scan: maximum range to search
|
| 964 | *
|
| 965 | * Search the set [index, min(index+max_scan-1, MAX_INDEX)] for the
|
| 966 | * lowest indexed hole.
|
| 967 | *
|
| 968 | * Returns: the index of the hole if found, otherwise returns an index
|
| 969 | * outside of the set specified (in which case 'return - index >=
|
| 970 | * max_scan' will be true). In rare cases of index wrap-around, 0 will
|
| 971 | * be returned.
|
| 972 | *
|
| 973 | * page_cache_next_hole may be called under rcu_read_lock. However,
|
| 974 | * like radix_tree_gang_lookup, this will not atomically search a
|
| 975 | * snapshot of the tree at a single point in time. For example, if a
|
| 976 | * hole is created at index 5, then subsequently a hole is created at
|
| 977 | * index 10, page_cache_next_hole covering both indexes may return 10
|
| 978 | * if called under rcu_read_lock.
|
| 979 |
|
| 980 | pgoff_t page_cache_next_hole(struct address_space *mapping,
|
| 981 | pgoff_t index, unsigned long max_scan)
|
| 982 | {
|
| 983 | unsigned long i;
|
| 984 |
|
| 985 | for (i = 0; i < max_scan; i++) {
|
| 986 | struct page *page;
|
| 987 |
|
| 988 | page = radix_tree_lookup(&mapping->page_tree, index);
|
| 989 | if (!page || radix_tree_exceptional_entry(page))
|
| 990 | break;
|
| 991 | index++;
|
| 992 | if (index == 0)
|
| 993 | break;
|
| 994 | }
|
| 995 |
|
| 996 | return index;
|
| 997 | }
|
| 998 | EXPORT_SYMBOL(page_cache_next_hole);
|
| 999 |
|
| 1000 | |
| 1001 | * page_cache_prev_hole - find the prev hole (not-present entry)
|
| 1002 | * @mapping: mapping
|
| 1003 | * @index: index
|
| 1004 | * @max_scan: maximum range to search
|
| 1005 | *
|
| 1006 | * Search backwards in the range [max(index-max_scan+1, 0), index] for
|
| 1007 | * the first hole.
|
| 1008 | *
|
| 1009 | * Returns: the index of the hole if found, otherwise returns an index
|
| 1010 | * outside of the set specified (in which case 'index - return >=
|
| 1011 | * max_scan' will be true). In rare cases of wrap-around, ULONG_MAX
|
| 1012 | * will be returned.
|
| 1013 | *
|
| 1014 | * page_cache_prev_hole may be called under rcu_read_lock. However,
|
| 1015 | * like radix_tree_gang_lookup, this will not atomically search a
|
| 1016 | * snapshot of the tree at a single point in time. For example, if a
|
| 1017 | * hole is created at index 10, then subsequently a hole is created at
|
| 1018 | * index 5, page_cache_prev_hole covering both indexes may return 5 if
|
| 1019 | * called under rcu_read_lock.
|
| 1020 |
|
| 1021 | pgoff_t page_cache_prev_hole(struct address_space *mapping,
|
| 1022 | pgoff_t index, unsigned long max_scan)
|
| 1023 | {
|
| 1024 | unsigned long i;
|
| 1025 |
|
| 1026 | for (i = 0; i < max_scan; i++) {
|
| 1027 | struct page *page;
|
| 1028 |
|
| 1029 | page = radix_tree_lookup(&mapping->page_tree, index);
|
| 1030 | if (!page || radix_tree_exceptional_entry(page))
|
| 1031 | break;
|
| 1032 | index--;
|
| 1033 | if (index == ULONG_MAX)
|
| 1034 | break;
|
| 1035 | }
|
| 1036 |
|
| 1037 | return index;
|
| 1038 | }
|
| 1039 | EXPORT_SYMBOL(page_cache_prev_hole);
|
| 1040 |
|
| 1041 | |
| 1042 | * find_get_entry - find and get a page cache entry
|
| 1043 | * @mapping: the address_space to search
|
| 1044 | * @offset: the page cache index
|
| 1045 | *
|
| 1046 | * Looks up the page cache slot at @mapping & @offset. If there is a
|
| 1047 | * page cache page, it is returned with an increased refcount.
|
| 1048 | *
|
| 1049 | * If the slot holds a shadow entry of a previously evicted page, or a
|
| 1050 | * swap entry from shmem/tmpfs, it is returned.
|
| 1051 | *
|
| 1052 | * Otherwise, %NULL is returned.
|
| 1053 |
|
| 1054 | struct page *find_get_entry(struct address_space *mapping, pgoff_t offset)
|
| 1055 | {
|
| 1056 | void **pagep;
|
| 1057 | struct page *page;
|
| 1058 |
|
| 1059 | rcu_read_lock();
|
| 1060 | repeat:
|
| 1061 | page = NULL;
|
| 1062 | pagep = radix_tree_lookup_slot(&mapping->page_tree, offset);
|
| 1063 | if (pagep) {
|
| 1064 | page = radix_tree_deref_slot(pagep);
|
| 1065 | if (unlikely(!page))
|
| 1066 | goto out;
|
| 1067 | if (radix_tree_exception(page)) {
|
| 1068 | if (radix_tree_deref_retry(page))
|
| 1069 | goto repeat;
|
| 1070 | |
| 1071 | * A shadow entry of a recently evicted page,
|
| 1072 | * or a swap entry from shmem/tmpfs. Return
|
| 1073 | * it without attempting to raise page count.
|
| 1074 |
|
| 1075 | goto out;
|
| 1076 | }
|
| 1077 | if (!page_cache_get_speculative(page))
|
| 1078 | goto repeat;
|
| 1079 |
|
| 1080 | |
| 1081 | * Has the page moved?
|
| 1082 | * This is part of the lockless pagecache protocol. See
|
| 1083 | * include/linux/pagemap.h for details.
|
| 1084 |
|
| 1085 | if (unlikely(page != *pagep)) {
|
| 1086 | put_page(page);
|
| 1087 | goto repeat;
|
| 1088 | }
|
| 1089 | }
|
| 1090 | out:
|
| 1091 | rcu_read_unlock();
|
| 1092 |
|
| 1093 | return page;
|
| 1094 | }
|
| 1095 | EXPORT_SYMBOL(find_get_entry);
|
| 1096 |
|
| 1097 | |
| 1098 | * find_lock_entry - locate, pin and lock a page cache entry
|
| 1099 | * @mapping: the address_space to search
|
| 1100 | * @offset: the page cache index
|
| 1101 | *
|
| 1102 | * Looks up the page cache slot at @mapping & @offset. If there is a
|
| 1103 | * page cache page, it is returned locked and with an increased
|
| 1104 | * refcount.
|
| 1105 | *
|
| 1106 | * If the slot holds a shadow entry of a previously evicted page, or a
|
| 1107 | * swap entry from shmem/tmpfs, it is returned.
|
| 1108 | *
|
| 1109 | * Otherwise, %NULL is returned.
|
| 1110 | *
|
| 1111 | * find_lock_entry() may sleep.
|
| 1112 |
|
| 1113 | struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset)
|
| 1114 | {
|
| 1115 | struct page *page;
|
| 1116 |
|
| 1117 | repeat:
|
| 1118 | page = find_get_entry(mapping, offset);
|
| 1119 | if (page && !radix_tree_exception(page)) {
|
| 1120 | lock_page(page);
|
| 1121 |
|
| 1122 | if (unlikely(page->mapping != mapping)) {
|
| 1123 | unlock_page(page);
|
| 1124 | put_page(page);
|
| 1125 | goto repeat;
|
| 1126 | }
|
| 1127 | VM_BUG_ON_PAGE(page->index != offset, page);
|
| 1128 | }
|
| 1129 | return page;
|
| 1130 | }
|
| 1131 | EXPORT_SYMBOL(find_lock_entry);
|
| 1132 |
|
| 1133 | |
| 1134 | * pagecache_get_page - find and get a page reference
|
| 1135 | * @mapping: the address_space to search
|
| 1136 | * @offset: the page index
|
| 1137 | * @fgp_flags: PCG flags
|
| 1138 | * @gfp_mask: gfp mask to use for the page cache data page allocation
|
| 1139 | *
|
| 1140 | * Looks up the page cache slot at @mapping & @offset.
|
| 1141 | *
|
| 1142 | * PCG flags modify how the page is returned.
|
| 1143 | *
|
| 1144 | * FGP_ACCESSED: the page will be marked accessed
|
| 1145 | * FGP_LOCK: Page is return locked
|
| 1146 | * FGP_CREAT: If page is not present then a new page is allocated using
|
| 1147 | * @gfp_mask and added to the page cache and the VM's LRU
|
| 1148 | * list. The page is returned locked and with an increased
|
| 1149 | * refcount. Otherwise, %NULL is returned.
|
| 1150 | *
|
| 1151 | * If FGP_LOCK or FGP_CREAT are specified then the function may sleep even
|
| 1152 | * if the GFP flags specified for FGP_CREAT are atomic.
|
| 1153 | *
|
| 1154 | * If there is a page cache page, it is returned with an increased refcount.
|
| 1155 |
|
| 1156 | struct page *pagecache_get_page(struct address_space *mapping, pgoff_t offset,
|
| 1157 | int fgp_flags, gfp_t gfp_mask)
|
| 1158 | {
|
| 1159 | struct page *page;
|
| 1160 |
|
| 1161 | repeat:
|
| 1162 | page = find_get_entry(mapping, offset);
|
| 1163 | if (radix_tree_exceptional_entry(page))
|
| 1164 | page = NULL;
|
| 1165 | if (!page)
|
| 1166 | goto no_page;
|
| 1167 |
|
| 1168 | if (fgp_flags & FGP_LOCK) {
|
| 1169 | if (fgp_flags & FGP_NOWAIT) {
|
| 1170 | if (!trylock_page(page)) {
|
| 1171 | put_page(page);
|
| 1172 | return NULL;
|
| 1173 | }
|
| 1174 | } else {
|
| 1175 | lock_page(page);
|
| 1176 | }
|
| 1177 |
|
| 1178 |
|
| 1179 | if (unlikely(page->mapping != mapping)) {
|
| 1180 | unlock_page(page);
|
| 1181 | put_page(page);
|
| 1182 | goto repeat;
|
| 1183 | }
|
| 1184 | VM_BUG_ON_PAGE(page->index != offset, page);
|
| 1185 | }
|
| 1186 |
|
| 1187 | if (page && (fgp_flags & FGP_ACCESSED))
|
| 1188 | mark_page_accessed(page);
|
| 1189 |
|
| 1190 | no_page:
|
| 1191 | if (!page && (fgp_flags & FGP_CREAT)) {
|
| 1192 | int err;
|
| 1193 | if ((fgp_flags & FGP_WRITE) && mapping_cap_account_dirty(mapping))
|
| 1194 | gfp_mask |= __GFP_WRITE;
|
| 1195 | if (fgp_flags & FGP_NOFS)
|
| 1196 | gfp_mask &= ~__GFP_FS;
|
| 1197 |
|
| 1198 | page = __page_cache_alloc(gfp_mask);
|
| 1199 | if (!page)
|
| 1200 | return NULL;
|
| 1201 |
|
| 1202 | if (WARN_ON_ONCE(!(fgp_flags & FGP_LOCK)))
|
| 1203 | fgp_flags |= FGP_LOCK;
|
| 1204 |
|
| 1205 |
|
| 1206 | if (fgp_flags & FGP_ACCESSED)
|
| 1207 | __SetPageReferenced(page);
|
| 1208 |
|
| 1209 | err = add_to_page_cache_lru(page, mapping, offset,
|
| 1210 | gfp_mask & GFP_RECLAIM_MASK);
|
| 1211 | if (unlikely(err)) {
|
| 1212 | put_page(page);
|
| 1213 | page = NULL;
|
| 1214 | if (err == -EEXIST)
|
| 1215 | goto repeat;
|
| 1216 | }
|
| 1217 | }
|
| 1218 |
|
| 1219 | return page;
|
| 1220 | }
|
| 1221 | EXPORT_SYMBOL(pagecache_get_page);
|
| 1222 |
|
| 1223 | |
| 1224 | * find_get_entries - gang pagecache lookup
|
| 1225 | * @mapping: The address_space to search
|
| 1226 | * @start: The starting page cache index
|
| 1227 | * @nr_entries: The maximum number of entries
|
| 1228 | * @entries: Where the resulting entries are placed
|
| 1229 | * @indices: The cache indices corresponding to the entries in @entries
|
| 1230 | *
|
| 1231 | * find_get_entries() will search for and return a group of up to
|
| 1232 | * @nr_entries entries in the mapping. The entries are placed at
|
| 1233 | * @entries. find_get_entries() takes a reference against any actual
|
| 1234 | * pages it returns.
|
| 1235 | *
|
| 1236 | * The search returns a group of mapping-contiguous page cache entries
|
| 1237 | * with ascending indexes. There may be holes in the indices due to
|
| 1238 | * not-present pages.
|
| 1239 | *
|
| 1240 | * Any shadow entries of evicted pages, or swap entries from
|
| 1241 | * shmem/tmpfs, are included in the returned array.
|
| 1242 | *
|
| 1243 | * find_get_entries() returns the number of pages and shadow entries
|
| 1244 | * which were found.
|
| 1245 |
|
| 1246 | unsigned find_get_entries(struct address_space *mapping,
|
| 1247 | pgoff_t start, unsigned int nr_entries,
|
| 1248 | struct page **entries, pgoff_t *indices)
|
| 1249 | {
|
| 1250 | void **slot;
|
| 1251 | unsigned int ret = 0;
|
| 1252 | struct radix_tree_iter iter;
|
| 1253 |
|
| 1254 | if (!nr_entries)
|
| 1255 | return 0;
|
| 1256 |
|
| 1257 | rcu_read_lock();
|
| 1258 | radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
|
| 1259 | struct page *page;
|
| 1260 | repeat:
|
| 1261 | page = radix_tree_deref_slot(slot);
|
| 1262 | if (unlikely(!page))
|
| 1263 | continue;
|
| 1264 | if (radix_tree_exception(page)) {
|
| 1265 | if (radix_tree_deref_retry(page)) {
|
| 1266 | slot = radix_tree_iter_retry(&iter);
|
| 1267 | continue;
|
| 1268 | }
|
| 1269 | |
| 1270 | * A shadow entry of a recently evicted page, a swap
|
| 1271 | * entry from shmem/tmpfs or a DAX entry. Return it
|
| 1272 | * without attempting to raise page count.
|
| 1273 |
|
| 1274 | goto export;
|
| 1275 | }
|
| 1276 | if (!page_cache_get_speculative(page))
|
| 1277 | goto repeat;
|
| 1278 |
|
| 1279 |
|
| 1280 | if (unlikely(page != *slot)) {
|
| 1281 | put_page(page);
|
| 1282 | goto repeat;
|
| 1283 | }
|
| 1284 | export:
|
| 1285 | indices[ret] = iter.index;
|
| 1286 | entries[ret] = page;
|
| 1287 | if (++ret == nr_entries)
|
| 1288 | break;
|
| 1289 | }
|
| 1290 | rcu_read_unlock();
|
| 1291 | return ret;
|
| 1292 | }
|
| 1293 |
|
| 1294 | |
| 1295 | * find_get_pages - gang pagecache lookup
|
| 1296 | * @mapping: The address_space to search
|
| 1297 | * @start: The starting page index
|
| 1298 | * @nr_pages: The maximum number of pages
|
| 1299 | * @pages: Where the resulting pages are placed
|
| 1300 | *
|
| 1301 | * find_get_pages() will search for and return a group of up to
|
| 1302 | * @nr_pages pages in the mapping. The pages are placed at @pages.
|
| 1303 | * find_get_pages() takes a reference against the returned pages.
|
| 1304 | *
|
| 1305 | * The search returns a group of mapping-contiguous pages with ascending
|
| 1306 | * indexes. There may be holes in the indices due to not-present pages.
|
| 1307 | *
|
| 1308 | * find_get_pages() returns the number of pages which were found.
|
| 1309 |
|
| 1310 | unsigned find_get_pages(struct address_space *mapping, pgoff_t start,
|
| 1311 | unsigned int nr_pages, struct page **pages)
|
| 1312 | {
|
| 1313 | struct radix_tree_iter iter;
|
| 1314 | void **slot;
|
| 1315 | unsigned ret = 0;
|
| 1316 |
|
| 1317 | if (unlikely(!nr_pages))
|
| 1318 | return 0;
|
| 1319 |
|
| 1320 | rcu_read_lock();
|
| 1321 | radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) {
|
| 1322 | struct page *page;
|
| 1323 | repeat:
|
| 1324 | page = radix_tree_deref_slot(slot);
|
| 1325 | if (unlikely(!page))
|
| 1326 | continue;
|
| 1327 |
|
| 1328 | if (radix_tree_exception(page)) {
|
| 1329 | if (radix_tree_deref_retry(page)) {
|
| 1330 | slot = radix_tree_iter_retry(&iter);
|
| 1331 | continue;
|
| 1332 | }
|
| 1333 | |
| 1334 | * A shadow entry of a recently evicted page,
|
| 1335 | * or a swap entry from shmem/tmpfs. Skip
|
| 1336 | * over it.
|
| 1337 |
|
| 1338 | continue;
|
| 1339 | }
|
| 1340 |
|
| 1341 | if (!page_cache_get_speculative(page))
|
| 1342 | goto repeat;
|
| 1343 |
|
| 1344 |
|
| 1345 | if (unlikely(page != *slot)) {
|
| 1346 | put_page(page);
|
| 1347 | goto repeat;
|
| 1348 | }
|
| 1349 |
|
| 1350 | pages[ret] = page;
|
| 1351 | if (++ret == nr_pages)
|
| 1352 | break;
|
| 1353 | }
|
| 1354 |
|
| 1355 | rcu_read_unlock();
|
| 1356 | return ret;
|
| 1357 | }
|
| 1358 |
|
| 1359 | |
| 1360 | * find_get_pages_contig - gang contiguous pagecache lookup
|
| 1361 | * @mapping: The address_space to search
|
| 1362 | * @index: The starting page index
|
| 1363 | * @nr_pages: The maximum number of pages
|
| 1364 | * @pages: Where the resulting pages are placed
|
| 1365 | *
|
| 1366 | * find_get_pages_contig() works exactly like find_get_pages(), except
|
| 1367 | * that the returned number of pages are guaranteed to be contiguous.
|
| 1368 | *
|
| 1369 | * find_get_pages_contig() returns the number of pages which were found.
|
| 1370 |
|
| 1371 | unsigned find_get_pages_contig(struct address_space *mapping, pgoff_t index,
|
| 1372 | unsigned int nr_pages, struct page **pages)
|
| 1373 | {
|
| 1374 | struct radix_tree_iter iter;
|
| 1375 | void **slot;
|
| 1376 | unsigned int ret = 0;
|
| 1377 |
|
| 1378 | if (unlikely(!nr_pages))
|
| 1379 | return 0;
|
| 1380 |
|
| 1381 | rcu_read_lock();
|
| 1382 | radix_tree_for_each_contig(slot, &mapping->page_tree, &iter, index) {
|
| 1383 | struct page *page;
|
| 1384 | repeat:
|
| 1385 | page = radix_tree_deref_slot(slot);
|
| 1386 |
|
| 1387 | if (unlikely(!page))
|
| 1388 | break;
|
| 1389 |
|
| 1390 | if (radix_tree_exception(page)) {
|
| 1391 | if (radix_tree_deref_retry(page)) {
|
| 1392 | slot = radix_tree_iter_retry(&iter);
|
| 1393 | continue;
|
| 1394 | }
|
| 1395 | |
| 1396 | * A shadow entry of a recently evicted page,
|
| 1397 | * or a swap entry from shmem/tmpfs. Stop
|
| 1398 | * looking for contiguous pages.
|
| 1399 |
|
| 1400 | break;
|
| 1401 | }
|
| 1402 |
|
| 1403 | if (!page_cache_get_speculative(page))
|
| 1404 | goto repeat;
|
| 1405 |
|
| 1406 |
|
| 1407 | if (unlikely(page != *slot)) {
|
| 1408 | put_page(page);
|
| 1409 | goto repeat;
|
| 1410 | }
|
| 1411 |
|
| 1412 | |
| 1413 | * must check mapping and index after taking the ref.
|
| 1414 | * otherwise we can get both false positives and false
|
| 1415 | * negatives, which is just confusing to the caller.
|
| 1416 |
|
| 1417 | if (page->mapping == NULL || page->index != iter.index) {
|
| 1418 | put_page(page);
|
| 1419 | break;
|
| 1420 | }
|
| 1421 |
|
| 1422 | pages[ret] = page;
|
| 1423 | if (++ret == nr_pages)
|
| 1424 | break;
|
| 1425 | }
|
| 1426 | rcu_read_unlock();
|
| 1427 | return ret;
|
| 1428 | }
|
| 1429 | EXPORT_SYMBOL(find_get_pages_contig);
|
| 1430 |
|
| 1431 | |
| 1432 | * find_get_pages_tag - find and return pages that match @tag
|
| 1433 | * @mapping: the address_space to search
|
| 1434 | * @index: the starting page index
|
| 1435 | * @tag: the tag index
|
| 1436 | * @nr_pages: the maximum number of pages
|
| 1437 | * @pages: where the resulting pages are placed
|
| 1438 | *
|
| 1439 | * Like find_get_pages, except we only return pages which are tagged with
|
| 1440 | * @tag. We update @index to index the next page for the traversal.
|
| 1441 |
|
| 1442 | unsigned find_get_pages_tag(struct address_space *mapping, pgoff_t *index,
|
| 1443 | int tag, unsigned int nr_pages, struct page **pages)
|
| 1444 | {
|
| 1445 | struct radix_tree_iter iter;
|
| 1446 | void **slot;
|
| 1447 | unsigned ret = 0;
|
| 1448 |
|
| 1449 | if (unlikely(!nr_pages))
|
| 1450 | return 0;
|
| 1451 |
|
| 1452 | rcu_read_lock();
|
| 1453 | radix_tree_for_each_tagged(slot, &mapping->page_tree,
|
| 1454 | &iter, *index, tag) {
|
| 1455 | struct page *page;
|
| 1456 | repeat:
|
| 1457 | page = radix_tree_deref_slot(slot);
|
| 1458 | if (unlikely(!page))
|
| 1459 | continue;
|
| 1460 |
|
| 1461 | if (radix_tree_exception(page)) {
|
| 1462 | if (radix_tree_deref_retry(page)) {
|
| 1463 | slot = radix_tree_iter_retry(&iter);
|
| 1464 | continue;
|
| 1465 | }
|
| 1466 | |
| 1467 | * A shadow entry of a recently evicted page.
|
| 1468 | *
|
| 1469 | * Those entries should never be tagged, but
|
| 1470 | * this tree walk is lockless and the tags are
|
| 1471 | * looked up in bulk, one radix tree node at a
|
| 1472 | * time, so there is a sizable window for page
|
| 1473 | * reclaim to evict a page we saw tagged.
|
| 1474 | *
|
| 1475 | * Skip over it.
|
| 1476 |
|
| 1477 | continue;
|
| 1478 | }
|
| 1479 |
|
| 1480 | if (!page_cache_get_speculative(page))
|
| 1481 | goto repeat;
|
| 1482 |
|
| 1483 |
|
| 1484 | if (unlikely(page != *slot)) {
|
| 1485 | put_page(page);
|
| 1486 | goto repeat;
|
| 1487 | }
|
| 1488 |
|
| 1489 | pages[ret] = page;
|
| 1490 | if (++ret == nr_pages)
|
| 1491 | break;
|
| 1492 | }
|
| 1493 |
|
| 1494 | rcu_read_unlock();
|
| 1495 |
|
| 1496 | if (ret)
|
| 1497 | *index = pages[ret - 1]->index + 1;
|
| 1498 |
|
| 1499 | return ret;
|
| 1500 | }
|
| 1501 | EXPORT_SYMBOL(find_get_pages_tag);
|
| 1502 |
|
| 1503 | |
| 1504 | * find_get_entries_tag - find and return entries that match @tag
|
| 1505 | * @mapping: the address_space to search
|
| 1506 | * @start: the starting page cache index
|
| 1507 | * @tag: the tag index
|
| 1508 | * @nr_entries: the maximum number of entries
|
| 1509 | * @entries: where the resulting entries are placed
|
| 1510 | * @indices: the cache indices corresponding to the entries in @entries
|
| 1511 | *
|
| 1512 | * Like find_get_entries, except we only return entries which are tagged with
|
| 1513 | * @tag.
|
| 1514 |
|
| 1515 | unsigned find_get_entries_tag(struct address_space *mapping, pgoff_t start,
|
| 1516 | int tag, unsigned int nr_entries,
|
| 1517 | struct page **entries, pgoff_t *indices)
|
| 1518 | {
|
| 1519 | void **slot;
|
| 1520 | unsigned int ret = 0;
|
| 1521 | struct radix_tree_iter iter;
|
| 1522 |
|
| 1523 | if (!nr_entries)
|
| 1524 | return 0;
|
| 1525 |
|
| 1526 | rcu_read_lock();
|
| 1527 | radix_tree_for_each_tagged(slot, &mapping->page_tree,
|
| 1528 | &iter, start, tag) {
|
| 1529 | struct page *page;
|
| 1530 | repeat:
|
| 1531 | page = radix_tree_deref_slot(slot);
|
| 1532 | if (unlikely(!page))
|
| 1533 | continue;
|
| 1534 | if (radix_tree_exception(page)) {
|
| 1535 | if (radix_tree_deref_retry(page)) {
|
| 1536 | slot = radix_tree_iter_retry(&iter);
|
| 1537 | continue;
|
| 1538 | }
|
| 1539 |
|
| 1540 | |
| 1541 | * A shadow entry of a recently evicted page, a swap
|
| 1542 | * entry from shmem/tmpfs or a DAX entry. Return it
|
| 1543 | * without attempting to raise page count.
|
| 1544 |
|
| 1545 | goto export;
|
| 1546 | }
|
| 1547 | if (!page_cache_get_speculative(page))
|
| 1548 | goto repeat;
|
| 1549 |
|
| 1550 |
|
| 1551 | if (unlikely(page != *slot)) {
|
| 1552 | put_page(page);
|
| 1553 | goto repeat;
|
| 1554 | }
|
| 1555 | export:
|
| 1556 | indices[ret] = iter.index;
|
| 1557 | entries[ret] = page;
|
| 1558 | if (++ret == nr_entries)
|
| 1559 | break;
|
| 1560 | }
|
| 1561 | rcu_read_unlock();
|
| 1562 | return ret;
|
| 1563 | }
|
| 1564 | EXPORT_SYMBOL(find_get_entries_tag);
|
| 1565 |
|
| 1566 | |
| 1567 | * CD/DVDs are error prone. When a medium error occurs, the driver may fail
|
| 1568 | * a _large_ part of the i/o request. Imagine the worst scenario:
|
| 1569 | *
|
| 1570 | * ---R__________________________________________B__________
|
| 1571 | * ^ reading here ^ bad block(assume 4k)
|
| 1572 | *
|
| 1573 | * read(R) => miss => readahead(R...B) => media error => frustrating retries
|
| 1574 | * => failing the whole request => read(R) => read(R+1) =>
|
| 1575 | * readahead(R+1...B+1) => bang => read(R+2) => read(R+3) =>
|
| 1576 | * readahead(R+3...B+2) => bang => read(R+3) => read(R+4) =>
|
| 1577 | * readahead(R+4...B+3) => bang => read(R+4) => read(R+5) => ......
|
| 1578 | *
|
| 1579 | * It is going insane. Fix it by quickly scaling down the readahead size.
|
| 1580 |
|
| 1581 | static void shrink_readahead_size_eio(struct file *filp,
|
| 1582 | struct file_ra_state *ra)
|
| 1583 | {
|
| 1584 | ra->ra_pages /= 4;
|
| 1585 | }
|
| 1586 |
|
| 1587 | |
| 1588 | * do_generic_file_read - generic file read routine
|
| 1589 | * @filp: the file to read
|
| 1590 | * @ppos: current file position
|
| 1591 | * @iter: data destination
|
| 1592 | * @written: already copied
|
| 1593 | *
|
| 1594 | * This is a generic file read routine, and uses the
|
| 1595 | * mapping->a_ops->readpage() function for the actual low-level stuff.
|
| 1596 | *
|
| 1597 | * This is really ugly. But the goto's actually try to clarify some
|
| 1598 | * of the logic when it comes to error handling etc.
|
| 1599 |
|
| 1600 | static ssize_t do_generic_file_read(struct file *filp, loff_t *ppos,
|
| 1601 | struct iov_iter *iter, ssize_t written)
|
| 1602 | {
|
| 1603 | struct address_space *mapping = filp->f_mapping;
|
| 1604 | struct inode *inode = mapping->host;
|
| 1605 | struct file_ra_state *ra = &filp->f_ra;
|
| 1606 | pgoff_t index;
|
| 1607 | pgoff_t last_index;
|
| 1608 | pgoff_t prev_index;
|
| 1609 | unsigned long offset;
|
| 1610 | unsigned int prev_offset;
|
| 1611 | int error = 0;
|
| 1612 |
|
| 1613 | index = *ppos >> PAGE_SHIFT;
|
| 1614 | prev_index = ra->prev_pos >> PAGE_SHIFT;
|
| 1615 | prev_offset = ra->prev_pos & (PAGE_SIZE-1);
|
| 1616 | last_index = (*ppos + iter->count + PAGE_SIZE-1) >> PAGE_SHIFT;
|
| 1617 | offset = *ppos & ~PAGE_MASK;
|
| 1618 |
|
| 1619 | for (;;) {
|
| 1620 | struct page *page;
|
| 1621 | pgoff_t end_index;
|
| 1622 | loff_t isize;
|
| 1623 | unsigned long nr, ret;
|
| 1624 |
|
| 1625 | cond_resched();
|
| 1626 | find_page:
|
| 1627 | page = find_get_page(mapping, index);
|
| 1628 | if (!page) {
|
| 1629 | page_cache_sync_readahead(mapping,
|
| 1630 | ra, filp,
|
| 1631 | index, last_index - index);
|
| 1632 | page = find_get_page(mapping, index);
|
| 1633 | if (unlikely(page == NULL))
|
| 1634 | goto no_cached_page;
|
| 1635 | }
|
| 1636 | if (PageReadahead(page)) {
|
| 1637 | page_cache_async_readahead(mapping,
|
| 1638 | ra, filp, page,
|
| 1639 | index, last_index - index);
|
| 1640 | }
|
| 1641 | if (!PageUptodate(page)) {
|
| 1642 | |
| 1643 | * See comment in do_read_cache_page on why
|
| 1644 | * wait_on_page_locked is used to avoid unnecessarily
|
| 1645 | * serialisations and why it's safe.
|
| 1646 |
|
| 1647 | wait_on_page_locked_killable(page);
|
| 1648 | if (PageUptodate(page))
|
| 1649 | goto page_ok;
|
| 1650 |
|
| 1651 | if (inode->i_blkbits == PAGE_SHIFT ||
|
| 1652 | !mapping->a_ops->is_partially_uptodate)
|
| 1653 | goto page_not_up_to_date;
|
| 1654 | if (!trylock_page(page))
|
| 1655 | goto page_not_up_to_date;
|
| 1656 |
|
| 1657 | if (!page->mapping)
|
| 1658 | goto page_not_up_to_date_locked;
|
| 1659 | if (!mapping->a_ops->is_partially_uptodate(page,
|
| 1660 | offset, iter->count))
|
| 1661 | goto page_not_up_to_date_locked;
|
| 1662 | unlock_page(page);
|
| 1663 | }
|
| 1664 | page_ok:
|
| 1665 | |
| 1666 | * i_size must be checked after we know the page is Uptodate.
|
| 1667 | *
|
| 1668 | * Checking i_size after the check allows us to calculate
|
| 1669 | * the correct value for "nr", which means the zero-filled
|
| 1670 | * part of the page is not copied back to userspace (unless
|
| 1671 | * another truncate extends the file - this is desired though).
|
| 1672 |
|
| 1673 |
|
| 1674 | isize = i_size_read(inode);
|
| 1675 | end_index = (isize - 1) >> PAGE_SHIFT;
|
| 1676 | if (unlikely(!isize || index > end_index)) {
|
| 1677 | put_page(page);
|
| 1678 | goto out;
|
| 1679 | }
|
| 1680 |
|
| 1681 |
|
| 1682 | nr = PAGE_SIZE;
|
| 1683 | if (index == end_index) {
|
| 1684 | nr = ((isize - 1) & ~PAGE_MASK) + 1;
|
| 1685 | if (nr <= offset) {
|
| 1686 | put_page(page);
|
| 1687 | goto out;
|
| 1688 | }
|
| 1689 | }
|
| 1690 | nr = nr - offset;
|
| 1691 |
|
| 1692 | |
| 1693 | * virtual addresses, take care about potential aliasing
|
| 1694 | * before reading the page on the kernel side.
|
| 1695 |
|
| 1696 | if (mapping_writably_mapped(mapping))
|
| 1697 | flush_dcache_page(page);
|
| 1698 |
|
| 1699 | |
| 1700 | * When a sequential read accesses a page several times,
|
| 1701 | * only mark it as accessed the first time.
|
| 1702 |
|
| 1703 | if (prev_index != index || offset != prev_offset)
|
| 1704 | mark_page_accessed(page);
|
| 1705 | prev_index = index;
|
| 1706 |
|
| 1707 | |
| 1708 | * Ok, we have the page, and it's up-to-date, so
|
| 1709 | * now we can copy it to user space...
|
| 1710 |
|
| 1711 |
|
| 1712 | ret = copy_page_to_iter(page, offset, nr, iter);
|
| 1713 | offset += ret;
|
| 1714 | index += offset >> PAGE_SHIFT;
|
| 1715 | offset &= ~PAGE_MASK;
|
| 1716 | prev_offset = offset;
|
| 1717 |
|
| 1718 | put_page(page);
|
| 1719 | written += ret;
|
| 1720 | if (!iov_iter_count(iter))
|
| 1721 | goto out;
|
| 1722 | if (ret < nr) {
|
| 1723 | error = -EFAULT;
|
| 1724 | goto out;
|
| 1725 | }
|
| 1726 | continue;
|
| 1727 |
|
| 1728 | page_not_up_to_date:
|
| 1729 |
|
| 1730 | error = lock_page_killable(page);
|
| 1731 | if (unlikely(error))
|
| 1732 | goto readpage_error;
|
| 1733 |
|
| 1734 | page_not_up_to_date_locked:
|
| 1735 |
|
| 1736 | if (!page->mapping) {
|
| 1737 | unlock_page(page);
|
| 1738 | put_page(page);
|
| 1739 | continue;
|
| 1740 | }
|
| 1741 |
|
| 1742 |
|
| 1743 | if (PageUptodate(page)) {
|
| 1744 | unlock_page(page);
|
| 1745 | goto page_ok;
|
| 1746 | }
|
| 1747 |
|
| 1748 | readpage:
|
| 1749 | |
| 1750 | * A previous I/O error may have been due to temporary
|
| 1751 | * failures, eg. multipath errors.
|
| 1752 | * PG_error will be set again if readpage fails.
|
| 1753 |
|
| 1754 | ClearPageError(page);
|
| 1755 |
|
| 1756 | error = mapping->a_ops->readpage(filp, page);
|
| 1757 |
|
| 1758 | if (unlikely(error)) {
|
| 1759 | if (error == AOP_TRUNCATED_PAGE) {
|
| 1760 | put_page(page);
|
| 1761 | error = 0;
|
| 1762 | goto find_page;
|
| 1763 | }
|
| 1764 | goto readpage_error;
|
| 1765 | }
|
| 1766 |
|
| 1767 | if (!PageUptodate(page)) {
|
| 1768 | error = lock_page_killable(page);
|
| 1769 | if (unlikely(error))
|
| 1770 | goto readpage_error;
|
| 1771 | if (!PageUptodate(page)) {
|
| 1772 | if (page->mapping == NULL) {
|
| 1773 | |
| 1774 | * invalidate_mapping_pages got it
|
| 1775 |
|
| 1776 | unlock_page(page);
|
| 1777 | put_page(page);
|
| 1778 | goto find_page;
|
| 1779 | }
|
| 1780 | unlock_page(page);
|
| 1781 | shrink_readahead_size_eio(filp, ra);
|
| 1782 | error = -EIO;
|
| 1783 | goto readpage_error;
|
| 1784 | }
|
| 1785 | unlock_page(page);
|
| 1786 | }
|
| 1787 |
|
| 1788 | goto page_ok;
|
| 1789 |
|
| 1790 | readpage_error:
|
| 1791 |
|
| 1792 | put_page(page);
|
| 1793 | goto out;
|
| 1794 |
|
| 1795 | no_cached_page:
|
| 1796 | |
| 1797 | * Ok, it wasn't cached, so we need to create a new
|
| 1798 | * page..
|
| 1799 |
|
| 1800 | page = page_cache_alloc_cold(mapping);
|
| 1801 | if (!page) {
|
| 1802 | error = -ENOMEM;
|
| 1803 | goto out;
|
| 1804 | }
|
| 1805 | error = add_to_page_cache_lru(page, mapping, index,
|
| 1806 | mapping_gfp_constraint(mapping, GFP_KERNEL));
|
| 1807 | if (error) {
|
| 1808 | put_page(page);
|
| 1809 | if (error == -EEXIST) {
|
| 1810 | error = 0;
|
| 1811 | goto find_page;
|
| 1812 | }
|
| 1813 | goto out;
|
| 1814 | }
|
| 1815 | goto readpage;
|
| 1816 | }
|
| 1817 |
|
| 1818 | out:
|
| 1819 | ra->prev_pos = prev_index;
|
| 1820 | ra->prev_pos <<= PAGE_SHIFT;
|
| 1821 | ra->prev_pos |= prev_offset;
|
| 1822 |
|
| 1823 | *ppos = ((loff_t)index << PAGE_SHIFT) + offset;
|
| 1824 | file_accessed(filp);
|
| 1825 | return written ? written : error;
|
| 1826 | }
|
| 1827 |
|
| 1828 | |
| 1829 | * generic_file_read_iter - generic filesystem read routine
|
| 1830 | * @iocb: kernel I/O control block
|
| 1831 | * @iter: destination for the data read
|
| 1832 | *
|
| 1833 | * This is the "read_iter()" routine for all filesystems
|
| 1834 | * that can use the page cache directly.
|
| 1835 |
|
| 1836 | ssize_t
|
| 1837 | generic_file_read_iter(struct kiocb *iocb, struct iov_iter *iter)
|
| 1838 | {
|
| 1839 | struct file *file = iocb->ki_filp;
|
| 1840 | ssize_t retval = 0;
|
| 1841 | loff_t *ppos = &iocb->ki_pos;
|
| 1842 | loff_t pos = *ppos;
|
| 1843 | size_t count = iov_iter_count(iter);
|
| 1844 |
|
| 1845 | if (!count)
|
| 1846 | goto out;
|
| 1847 |
|
| 1848 | if (iocb->ki_flags & IOCB_DIRECT) {
|
| 1849 | struct address_space *mapping = file->f_mapping;
|
| 1850 | struct inode *inode = mapping->host;
|
| 1851 | loff_t size;
|
| 1852 |
|
| 1853 | size = i_size_read(inode);
|
| 1854 | retval = filemap_write_and_wait_range(mapping, pos,
|
| 1855 | pos + count - 1);
|
| 1856 | if (!retval) {
|
| 1857 | struct iov_iter data = *iter;
|
| 1858 | retval = mapping->a_ops->direct_IO(iocb, &data, pos);
|
| 1859 | }
|
| 1860 |
|
| 1861 | if (retval > 0) {
|
| 1862 | *ppos = pos + retval;
|
| 1863 | iov_iter_advance(iter, retval);
|
| 1864 | }
|
| 1865 |
|
| 1866 | |
| 1867 | * Btrfs can have a short DIO read if we encounter
|
| 1868 | * compressed extents, so if there was an error, or if
|
| 1869 | * we've already read everything we wanted to, or if
|
| 1870 | * there was a short read because we hit EOF, go ahead
|
| 1871 | * and return. Otherwise fallthrough to buffered io for
|
| 1872 | * the rest of the read. Buffered reads will not work for
|
| 1873 | * DAX files, so don't bother trying.
|
| 1874 |
|
| 1875 | if (retval < 0 || !iov_iter_count(iter) || *ppos >= size ||
|
| 1876 | IS_DAX(inode)) {
|
| 1877 | file_accessed(file);
|
| 1878 | goto out;
|
| 1879 | }
|
| 1880 | }
|
| 1881 |
|
| 1882 | retval = do_generic_file_read(file, ppos, iter, retval);
|
| 1883 | out:
|
| 1884 | return retval;
|
| 1885 | }
|
| 1886 | EXPORT_SYMBOL(generic_file_read_iter);
|
| 1887 |
|
| 1888 | #ifdef CONFIG_MMU
|
| 1889 | |
| 1890 | * page_cache_read - adds requested page to the page cache if not already there
|
| 1891 | * @file: file to read
|
| 1892 | * @offset: page index
|
| 1893 | * @gfp_mask: memory allocation flags
|
| 1894 | *
|
| 1895 | * This adds the requested page to the page cache if it isn't already there,
|
| 1896 | * and schedules an I/O to read in its contents from disk.
|
| 1897 |
|
| 1898 | static int page_cache_read(struct file *file, pgoff_t offset, gfp_t gfp_mask)
|
| 1899 | {
|
| 1900 | struct address_space *mapping = file->f_mapping;
|
| 1901 | struct page *page;
|
| 1902 | int ret;
|
| 1903 |
|
| 1904 | do {
|
| 1905 | page = __page_cache_alloc(gfp_mask|__GFP_COLD);
|
| 1906 | if (!page)
|
| 1907 | return -ENOMEM;
|
| 1908 |
|
| 1909 | ret = add_to_page_cache_lru(page, mapping, offset, gfp_mask & GFP_KERNEL);
|
| 1910 | if (ret == 0)
|
| 1911 | ret = mapping->a_ops->readpage(file, page);
|
| 1912 | else if (ret == -EEXIST)
|
| 1913 | ret = 0;
|
| 1914 |
|
| 1915 | put_page(page);
|
| 1916 |
|
| 1917 | } while (ret == AOP_TRUNCATED_PAGE);
|
| 1918 |
|
| 1919 | return ret;
|
| 1920 | }
|
| 1921 |
|
| 1922 | #define MMAP_LOTSAMISS (100)
|
| 1923 |
|
| 1924 | |
| 1925 | * Synchronous readahead happens when we don't even find
|
| 1926 | * a page in the page cache at all.
|
| 1927 |
|
| 1928 | static void do_sync_mmap_readahead(struct vm_area_struct *vma,
|
| 1929 | struct file_ra_state *ra,
|
| 1930 | struct file *file,
|
| 1931 | pgoff_t offset)
|
| 1932 | {
|
| 1933 | struct address_space *mapping = file->f_mapping;
|
| 1934 |
|
| 1935 |
|
| 1936 | if (vma->vm_flags & VM_RAND_READ)
|
| 1937 | return;
|
| 1938 | if (!ra->ra_pages)
|
| 1939 | return;
|
| 1940 |
|
| 1941 | if (vma->vm_flags & VM_SEQ_READ) {
|
| 1942 | page_cache_sync_readahead(mapping, ra, file, offset,
|
| 1943 | ra->ra_pages);
|
| 1944 | return;
|
| 1945 | }
|
| 1946 |
|
| 1947 |
|
| 1948 | if (ra->mmap_miss < MMAP_LOTSAMISS * 10)
|
| 1949 | ra->mmap_miss++;
|
| 1950 |
|
| 1951 | |
| 1952 | * Do we miss much more than hit in this file? If so,
|
| 1953 | * stop bothering with read-ahead. It will only hurt.
|
| 1954 |
|
| 1955 | if (ra->mmap_miss > MMAP_LOTSAMISS)
|
| 1956 | return;
|
| 1957 |
|
| 1958 | |
| 1959 | * mmap read-around
|
| 1960 |
|
| 1961 | ra->start = max_t(long, 0, offset - ra->ra_pages / 2);
|
| 1962 | ra->size = ra->ra_pages;
|
| 1963 | ra->async_size = ra->ra_pages / 4;
|
| 1964 | ra_submit(ra, mapping, file);
|
| 1965 | }
|
| 1966 |
|
| 1967 | |
| 1968 | * Asynchronous readahead happens when we find the page and PG_readahead,
|
| 1969 | * so we want to possibly extend the readahead further..
|
| 1970 |
|
| 1971 | static void do_async_mmap_readahead(struct vm_area_struct *vma,
|
| 1972 | struct file_ra_state *ra,
|
| 1973 | struct file *file,
|
| 1974 | struct page *page,
|
| 1975 | pgoff_t offset)
|
| 1976 | {
|
| 1977 | struct address_space *mapping = file->f_mapping;
|
| 1978 |
|
| 1979 |
|
| 1980 | if (vma->vm_flags & VM_RAND_READ)
|
| 1981 | return;
|
| 1982 | if (ra->mmap_miss > 0)
|
| 1983 | ra->mmap_miss--;
|
| 1984 | if (PageReadahead(page))
|
| 1985 | page_cache_async_readahead(mapping, ra, file,
|
| 1986 | page, offset, ra->ra_pages);
|
| 1987 | }
|
| 1988 |
|
| 1989 | |
| 1990 | * filemap_fault - read in file data for page fault handling
|
| 1991 | * @vma: vma in which the fault was taken
|
| 1992 | * @vmf: struct vm_fault containing details of the fault
|
| 1993 | *
|
| 1994 | * filemap_fault() is invoked via the vma operations vector for a
|
| 1995 | * mapped memory region to read in file data during a page fault.
|
| 1996 | *
|
| 1997 | * The goto's are kind of ugly, but this streamlines the normal case of having
|
| 1998 | * it in the page cache, and handles the special cases reasonably without
|
| 1999 | * having a lot of duplicated code.
|
| 2000 | *
|
| 2001 | * vma->vm_mm->mmap_sem must be held on entry.
|
| 2002 | *
|
| 2003 | * If our return value has VM_FAULT_RETRY set, it's because
|
| 2004 | * lock_page_or_retry() returned 0.
|
| 2005 | * The mmap_sem has usually been released in this case.
|
| 2006 | * See __lock_page_or_retry() for the exception.
|
| 2007 | *
|
| 2008 | * If our return value does not have VM_FAULT_RETRY set, the mmap_sem
|
| 2009 | * has not been released.
|
| 2010 | *
|
| 2011 | * We never return with VM_FAULT_RETRY and a bit from VM_FAULT_ERROR set.
|
| 2012 |
|
| 2013 | int filemap_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
|
| 2014 | {
|
| 2015 | int error;
|
| 2016 | struct file *file = vma->vm_file;
|
| 2017 | struct address_space *mapping = file->f_mapping;
|
| 2018 | struct file_ra_state *ra = &file->f_ra;
|
| 2019 | struct inode *inode = mapping->host;
|
| 2020 | pgoff_t offset = vmf->pgoff;
|
| 2021 | struct page *page;
|
| 2022 | loff_t size;
|
| 2023 | int ret = 0;
|
| 2024 |
|
| 2025 | size = round_up(i_size_read(inode), PAGE_SIZE);
|
| 2026 | if (offset >= size >> PAGE_SHIFT)
|
| 2027 | return VM_FAULT_SIGBUS;
|
| 2028 |
|
| 2029 | |
| 2030 | * Do we have something in the page cache already?
|
| 2031 |
|
| 2032 | page = find_get_page(mapping, offset);
|
| 2033 | if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
|
| 2034 | |
| 2035 | * We found the page, so try async readahead before
|
| 2036 | * waiting for the lock.
|
| 2037 |
|
| 2038 | do_async_mmap_readahead(vma, ra, file, page, offset);
|
| 2039 | } else if (!page) {
|
| 2040 |
|
| 2041 | do_sync_mmap_readahead(vma, ra, file, offset);
|
| 2042 | count_vm_event(PGMAJFAULT);
|
| 2043 | mem_cgroup_count_vm_event(vma->vm_mm, PGMAJFAULT);
|
| 2044 | ret = VM_FAULT_MAJOR;
|
| 2045 | retry_find:
|
| 2046 | page = find_get_page(mapping, offset);
|
| 2047 | if (!page)
|
| 2048 | goto no_cached_page;
|
| 2049 | }
|
| 2050 |
|
| 2051 | if (!lock_page_or_retry(page, vma->vm_mm, vmf->flags)) {
|
| 2052 | put_page(page);
|
| 2053 | return ret | VM_FAULT_RETRY;
|
| 2054 | }
|
| 2055 |
|
| 2056 |
|
| 2057 | if (unlikely(page->mapping != mapping)) {
|
| 2058 | unlock_page(page);
|
| 2059 | put_page(page);
|
| 2060 | goto retry_find;
|
| 2061 | }
|
| 2062 | VM_BUG_ON_PAGE(page->index != offset, page);
|
| 2063 |
|
| 2064 | |
| 2065 | * We have a locked page in the page cache, now we need to check
|
| 2066 | * that it's up-to-date. If not, it is going to be due to an error.
|
| 2067 |
|
| 2068 | if (unlikely(!PageUptodate(page)))
|
| 2069 | goto page_not_uptodate;
|
| 2070 |
|
| 2071 | |
| 2072 | * Found the page and have a reference on it.
|
| 2073 | * We must recheck i_size under page lock.
|
| 2074 |
|
| 2075 | size = round_up(i_size_read(inode), PAGE_SIZE);
|
| 2076 | if (unlikely(offset >= size >> PAGE_SHIFT)) {
|
| 2077 | unlock_page(page);
|
| 2078 | put_page(page);
|
| 2079 | return VM_FAULT_SIGBUS;
|
| 2080 | }
|
| 2081 |
|
| 2082 | vmf->page = page;
|
| 2083 | return ret | VM_FAULT_LOCKED;
|
| 2084 |
|
| 2085 | no_cached_page:
|
| 2086 | |
| 2087 | * We're only likely to ever get here if MADV_RANDOM is in
|
| 2088 | * effect.
|
| 2089 |
|
| 2090 | error = page_cache_read(file, offset, vmf->gfp_mask);
|
| 2091 |
|
| 2092 | |
| 2093 | * The page we want has now been added to the page cache.
|
| 2094 | * In the unlikely event that someone removed it in the
|
| 2095 | * meantime, we'll just come back here and read it again.
|
| 2096 |
|
| 2097 | if (error >= 0)
|
| 2098 | goto retry_find;
|
| 2099 |
|
| 2100 | |
| 2101 | * An error return from page_cache_read can result if the
|
| 2102 | * system is low on memory, or a problem occurs while trying
|
| 2103 | * to schedule I/O.
|
| 2104 |
|
| 2105 | if (error == -ENOMEM)
|
| 2106 | return VM_FAULT_OOM;
|
| 2107 | return VM_FAULT_SIGBUS;
|
| 2108 |
|
| 2109 | page_not_uptodate:
|
| 2110 | |
| 2111 | * Umm, take care of errors if the page isn't up-to-date.
|
| 2112 | * Try to re-read it _once_. We do this synchronously,
|
| 2113 | * because there really aren't any performance issues here
|
| 2114 | * and we need to check for errors.
|
| 2115 |
|
| 2116 | ClearPageError(page);
|
| 2117 | error = mapping->a_ops->readpage(file, page);
|
| 2118 | if (!error) {
|
| 2119 | wait_on_page_locked(page);
|
| 2120 | if (!PageUptodate(page))
|
| 2121 | error = -EIO;
|
| 2122 | }
|
| 2123 | put_page(page);
|
| 2124 |
|
| 2125 | if (!error || error == AOP_TRUNCATED_PAGE)
|
| 2126 | goto retry_find;
|
| 2127 |
|
| 2128 |
|
| 2129 | shrink_readahead_size_eio(file, ra);
|
| 2130 | return VM_FAULT_SIGBUS;
|
| 2131 | }
|
| 2132 | EXPORT_SYMBOL(filemap_fault);
|
| 2133 |
|
| 2134 | void filemap_map_pages(struct vm_area_struct *vma, struct vm_fault *vmf)
|
| 2135 | {
|
| 2136 | struct radix_tree_iter iter;
|
| 2137 | void **slot;
|
| 2138 | struct file *file = vma->vm_file;
|
| 2139 | struct address_space *mapping = file->f_mapping;
|
| 2140 | loff_t size;
|
| 2141 | struct page *page;
|
| 2142 | unsigned long address = (unsigned long) vmf->virtual_address;
|
| 2143 | unsigned long addr;
|
| 2144 | pte_t *pte;
|
| 2145 |
|
| 2146 | rcu_read_lock();
|
| 2147 | radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, vmf->pgoff) {
|
| 2148 | if (iter.index > vmf->max_pgoff)
|
| 2149 | break;
|
| 2150 | repeat:
|
| 2151 | page = radix_tree_deref_slot(slot);
|
| 2152 | if (unlikely(!page))
|
| 2153 | goto next;
|
| 2154 | if (radix_tree_exception(page)) {
|
| 2155 | if (radix_tree_deref_retry(page)) {
|
| 2156 | slot = radix_tree_iter_retry(&iter);
|
| 2157 | continue;
|
| 2158 | }
|
| 2159 | goto next;
|
| 2160 | }
|
| 2161 |
|
| 2162 | if (!page_cache_get_speculative(page))
|
| 2163 | goto repeat;
|
| 2164 |
|
| 2165 |
|
| 2166 | if (unlikely(page != *slot)) {
|
| 2167 | put_page(page);
|
| 2168 | goto repeat;
|
| 2169 | }
|
| 2170 |
|
| 2171 | if (!PageUptodate(page) ||
|
| 2172 | PageReadahead(page) ||
|
| 2173 | PageHWPoison(page))
|
| 2174 | goto skip;
|
| 2175 | if (!trylock_page(page))
|
| 2176 | goto skip;
|
| 2177 |
|
| 2178 | if (page->mapping != mapping || !PageUptodate(page))
|
| 2179 | goto unlock;
|
| 2180 |
|
| 2181 | size = round_up(i_size_read(mapping->host), PAGE_SIZE);
|
| 2182 | if (page->index >= size >> PAGE_SHIFT)
|
| 2183 | goto unlock;
|
| 2184 |
|
| 2185 | pte = vmf->pte + page->index - vmf->pgoff;
|
| 2186 | if (!pte_none(*pte))
|
| 2187 | goto unlock;
|
| 2188 |
|
| 2189 | if (file->f_ra.mmap_miss > 0)
|
| 2190 | file->f_ra.mmap_miss--;
|
| 2191 | addr = address + (page->index - vmf->pgoff) * PAGE_SIZE;
|
| 2192 | do_set_pte(vma, addr, page, pte, false, false);
|
| 2193 | unlock_page(page);
|
| 2194 | goto next;
|
| 2195 | unlock:
|
| 2196 | unlock_page(page);
|
| 2197 | skip:
|
| 2198 | put_page(page);
|
| 2199 | next:
|
| 2200 | if (iter.index == vmf->max_pgoff)
|
| 2201 | break;
|
| 2202 | }
|
| 2203 | rcu_read_unlock();
|
| 2204 | }
|
| 2205 | EXPORT_SYMBOL(filemap_map_pages);
|
| 2206 |
|
| 2207 | int filemap_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf)
|
| 2208 | {
|
| 2209 | struct page *page = vmf->page;
|
| 2210 | struct inode *inode = file_inode(vma->vm_file);
|
| 2211 | int ret = VM_FAULT_LOCKED;
|
| 2212 |
|
| 2213 | sb_start_pagefault(inode->i_sb);
|
| 2214 | file_update_time(vma->vm_file);
|
| 2215 | lock_page(page);
|
| 2216 | if (page->mapping != inode->i_mapping) {
|
| 2217 | unlock_page(page);
|
| 2218 | ret = VM_FAULT_NOPAGE;
|
| 2219 | goto out;
|
| 2220 | }
|
| 2221 | |
| 2222 | * We mark the page dirty already here so that when freeze is in
|
| 2223 | * progress, we are guaranteed that writeback during freezing will
|
| 2224 | * see the dirty page and writeprotect it again.
|
| 2225 |
|
| 2226 | set_page_dirty(page);
|
| 2227 | wait_for_stable_page(page);
|
| 2228 | out:
|
| 2229 | sb_end_pagefault(inode->i_sb);
|
| 2230 | return ret;
|
| 2231 | }
|
| 2232 | EXPORT_SYMBOL(filemap_page_mkwrite);
|
| 2233 |
|
| 2234 | const struct vm_operations_struct generic_file_vm_ops = {
|
| 2235 | .fault = filemap_fault,
|
| 2236 | .map_pages = filemap_map_pages,
|
| 2237 | .page_mkwrite = filemap_page_mkwrite,
|
| 2238 | };
|
| 2239 |
|
| 2240 |
|
| 2241 |
|
| 2242 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
|
| 2243 | {
|
| 2244 | struct address_space *mapping = file->f_mapping;
|
| 2245 |
|
| 2246 | if (!mapping->a_ops->readpage)
|
| 2247 | return -ENOEXEC;
|
| 2248 | file_accessed(file);
|
| 2249 | vma->vm_ops = &generic_file_vm_ops;
|
| 2250 | return 0;
|
| 2251 | }
|
| 2252 |
|
| 2253 | |
| 2254 | * This is for filesystems which do not implement ->writepage.
|
| 2255 |
|
| 2256 | int generic_file_readonly_mmap(struct file *file, struct vm_area_struct *vma)
|
| 2257 | {
|
| 2258 | if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_MAYWRITE))
|
| 2259 | return -EINVAL;
|
| 2260 | return generic_file_mmap(file, vma);
|
| 2261 | }
|
| 2262 | #else
|
| 2263 | int generic_file_mmap(struct file * file, struct vm_area_struct * vma)
|
| 2264 | {
|
| 2265 | return -ENOSYS;
|
| 2266 | }
|
| 2267 | int generic_file_readonly_mmap(struct file * file, struct vm_area_struct * vma)
|
| 2268 | {
|
| 2269 | return -ENOSYS;
|
| 2270 | }
|
| 2271 | #endif
|
| 2272 |
|
| 2273 | EXPORT_SYMBOL(generic_file_mmap);
|
| 2274 | EXPORT_SYMBOL(generic_file_readonly_mmap);
|
| 2275 |
|
| 2276 | static struct page *wait_on_page_read(struct page *page)
|
| 2277 | {
|
| 2278 | if (!IS_ERR(page)) {
|
| 2279 | wait_on_page_locked(page);
|
| 2280 | if (!PageUptodate(page)) {
|
| 2281 | put_page(page);
|
| 2282 | page = ERR_PTR(-EIO);
|
| 2283 | }
|
| 2284 | }
|
| 2285 | return page;
|
| 2286 | }
|
| 2287 |
|
| 2288 | static struct page *do_read_cache_page(struct address_space *mapping,
|
| 2289 | pgoff_t index,
|
| 2290 | int (*filler)(void *, struct page *),
|
| 2291 | void *data,
|
| 2292 | gfp_t gfp)
|
| 2293 | {
|
| 2294 | struct page *page;
|
| 2295 | int err;
|
| 2296 | repeat:
|
| 2297 | page = find_get_page(mapping, index);
|
| 2298 | if (!page) {
|
| 2299 | page = __page_cache_alloc(gfp | __GFP_COLD);
|
| 2300 | if (!page)
|
| 2301 | return ERR_PTR(-ENOMEM);
|
| 2302 | err = add_to_page_cache_lru(page, mapping, index, gfp);
|
| 2303 | if (unlikely(err)) {
|
| 2304 | put_page(page);
|
| 2305 | if (err == -EEXIST)
|
| 2306 | goto repeat;
|
| 2307 |
|
| 2308 | return ERR_PTR(err);
|
| 2309 | }
|
| 2310 |
|
| 2311 | filler:
|
| 2312 | err = filler(data, page);
|
| 2313 | if (err < 0) {
|
| 2314 | put_page(page);
|
| 2315 | return ERR_PTR(err);
|
| 2316 | }
|
| 2317 |
|
| 2318 | page = wait_on_page_read(page);
|
| 2319 | if (IS_ERR(page))
|
| 2320 | return page;
|
| 2321 | goto out;
|
| 2322 | }
|
| 2323 | if (PageUptodate(page))
|
| 2324 | goto out;
|
| 2325 |
|
| 2326 | |
| 2327 | * Page is not up to date and may be locked due one of the following
|
| 2328 | * case a: Page is being filled and the page lock is held
|
| 2329 | * case b: Read/write error clearing the page uptodate status
|
| 2330 | * case c: Truncation in progress (page locked)
|
| 2331 | * case d: Reclaim in progress
|
| 2332 | *
|
| 2333 | * Case a, the page will be up to date when the page is unlocked.
|
| 2334 | * There is no need to serialise on the page lock here as the page
|
| 2335 | * is pinned so the lock gives no additional protection. Even if the
|
| 2336 | * the page is truncated, the data is still valid if PageUptodate as
|
| 2337 | * it's a race vs truncate race.
|
| 2338 | * Case b, the page will not be up to date
|
| 2339 | * Case c, the page may be truncated but in itself, the data may still
|
| 2340 | * be valid after IO completes as it's a read vs truncate race. The
|
| 2341 | * operation must restart if the page is not uptodate on unlock but
|
| 2342 | * otherwise serialising on page lock to stabilise the mapping gives
|
| 2343 | * no additional guarantees to the caller as the page lock is
|
| 2344 | * released before return.
|
| 2345 | * Case d, similar to truncation. If reclaim holds the page lock, it
|
| 2346 | * will be a race with remove_mapping that determines if the mapping
|
| 2347 | * is valid on unlock but otherwise the data is valid and there is
|
| 2348 | * no need to serialise with page lock.
|
| 2349 | *
|
| 2350 | * As the page lock gives no additional guarantee, we optimistically
|
| 2351 | * wait on the page to be unlocked and check if it's up to date and
|
| 2352 | * use the page if it is. Otherwise, the page lock is required to
|
| 2353 | * distinguish between the different cases. The motivation is that we
|
| 2354 | * avoid spurious serialisations and wakeups when multiple processes
|
| 2355 | * wait on the same page for IO to complete.
|
| 2356 |
|
| 2357 | wait_on_page_locked(page);
|
| 2358 | if (PageUptodate(page))
|
| 2359 | goto out;
|
| 2360 |
|
| 2361 |
|
| 2362 | lock_page(page);
|
| 2363 |
|
| 2364 |
|
| 2365 | if (!page->mapping) {
|
| 2366 | unlock_page(page);
|
| 2367 | put_page(page);
|
| 2368 | goto repeat;
|
| 2369 | }
|
| 2370 |
|
| 2371 |
|
| 2372 | if (PageUptodate(page)) {
|
| 2373 | unlock_page(page);
|
| 2374 | goto out;
|
| 2375 | }
|
| 2376 | goto filler;
|
| 2377 |
|
| 2378 | out:
|
| 2379 | mark_page_accessed(page);
|
| 2380 | return page;
|
| 2381 | }
|
| 2382 |
|
| 2383 | |
| 2384 | * read_cache_page - read into page cache, fill it if needed
|
| 2385 | * @mapping: the page's address_space
|
| 2386 | * @index: the page index
|
| 2387 | * @filler: function to perform the read
|
| 2388 | * @data: first arg to filler(data, page) function, often left as NULL
|
| 2389 | *
|
| 2390 | * Read into the page cache. If a page already exists, and PageUptodate() is
|
| 2391 | * not set, try to fill the page and wait for it to become unlocked.
|
| 2392 | *
|
| 2393 | * If the page does not get brought uptodate, return -EIO.
|
| 2394 |
|
| 2395 | struct page *read_cache_page(struct address_space *mapping,
|
| 2396 | pgoff_t index,
|
| 2397 | int (*filler)(void *, struct page *),
|
| 2398 | void *data)
|
| 2399 | {
|
| 2400 | return do_read_cache_page(mapping, index, filler, data, mapping_gfp_mask(mapping));
|
| 2401 | }
|
| 2402 | EXPORT_SYMBOL(read_cache_page);
|
| 2403 |
|
| 2404 | |
| 2405 | * read_cache_page_gfp - read into page cache, using specified page allocation flags.
|
| 2406 | * @mapping: the page's address_space
|
| 2407 | * @index: the page index
|
| 2408 | * @gfp: the page allocator flags to use if allocating
|
| 2409 | *
|
| 2410 | * This is the same as "read_mapping_page(mapping, index, NULL)", but with
|
| 2411 | * any new page allocations done using the specified allocation flags.
|
| 2412 | *
|
| 2413 | * If the page does not get brought uptodate, return -EIO.
|
| 2414 |
|
| 2415 | struct page *read_cache_page_gfp(struct address_space *mapping,
|
| 2416 | pgoff_t index,
|
| 2417 | gfp_t gfp)
|
| 2418 | {
|
| 2419 | filler_t *filler = (filler_t *)mapping->a_ops->readpage;
|
| 2420 |
|
| 2421 | return do_read_cache_page(mapping, index, filler, NULL, gfp);
|
| 2422 | }
|
| 2423 | EXPORT_SYMBOL(read_cache_page_gfp);
|
| 2424 |
|
| 2425 | |
| 2426 | * Performs necessary checks before doing a write
|
| 2427 | *
|
| 2428 | * Can adjust writing position or amount of bytes to write.
|
| 2429 | * Returns appropriate error code that caller should return or
|
| 2430 | * zero in case that write should be allowed.
|
| 2431 |
|
| 2432 | inline ssize_t generic_write_checks(struct kiocb *iocb, struct iov_iter *from)
|
| 2433 | {
|
| 2434 | struct file *file = iocb->ki_filp;
|
| 2435 | struct inode *inode = file->f_mapping->host;
|
| 2436 | unsigned long limit = rlimit(RLIMIT_FSIZE);
|
| 2437 | loff_t pos;
|
| 2438 |
|
| 2439 | if (!iov_iter_count(from))
|
| 2440 | return 0;
|
| 2441 |
|
| 2442 |
|
| 2443 | if (iocb->ki_flags & IOCB_APPEND)
|
| 2444 | iocb->ki_pos = i_size_read(inode);
|
| 2445 |
|
| 2446 | pos = iocb->ki_pos;
|
| 2447 |
|
| 2448 | if (limit != RLIM_INFINITY) {
|
| 2449 | if (iocb->ki_pos >= limit) {
|
| 2450 | send_sig(SIGXFSZ, current, 0);
|
| 2451 | return -EFBIG;
|
| 2452 | }
|
| 2453 | iov_iter_truncate(from, limit - (unsigned long)pos);
|
| 2454 | }
|
| 2455 |
|
| 2456 | |
| 2457 | * LFS rule
|
| 2458 |
|
| 2459 | if (unlikely(pos + iov_iter_count(from) > MAX_NON_LFS &&
|
| 2460 | !(file->f_flags & O_LARGEFILE))) {
|
| 2461 | if (pos >= MAX_NON_LFS)
|
| 2462 | return -EFBIG;
|
| 2463 | iov_iter_truncate(from, MAX_NON_LFS - (unsigned long)pos);
|
| 2464 | }
|
| 2465 |
|
| 2466 | |
| 2467 | * Are we about to exceed the fs block limit ?
|
| 2468 | *
|
| 2469 | * If we have written data it becomes a short write. If we have
|
| 2470 | * exceeded without writing data we send a signal and return EFBIG.
|
| 2471 | * Linus frestrict idea will clean these up nicely..
|
| 2472 |
|
| 2473 | if (unlikely(pos >= inode->i_sb->s_maxbytes))
|
| 2474 | return -EFBIG;
|
| 2475 |
|
| 2476 | iov_iter_truncate(from, inode->i_sb->s_maxbytes - pos);
|
| 2477 | return iov_iter_count(from);
|
| 2478 | }
|
| 2479 | EXPORT_SYMBOL(generic_write_checks);
|
| 2480 |
|
| 2481 | int pagecache_write_begin(struct file *file, struct address_space *mapping,
|
| 2482 | loff_t pos, unsigned len, unsigned flags,
|
| 2483 | struct page **pagep, void **fsdata)
|
| 2484 | {
|
| 2485 | const struct address_space_operations *aops = mapping->a_ops;
|
| 2486 |
|
| 2487 | return aops->write_begin(file, mapping, pos, len, flags,
|
| 2488 | pagep, fsdata);
|
| 2489 | }
|
| 2490 | EXPORT_SYMBOL(pagecache_write_begin);
|
| 2491 |
|
| 2492 | int pagecache_write_end(struct file *file, struct address_space *mapping,
|
| 2493 | loff_t pos, unsigned len, unsigned copied,
|
| 2494 | struct page *page, void *fsdata)
|
| 2495 | {
|
| 2496 | const struct address_space_operations *aops = mapping->a_ops;
|
| 2497 |
|
| 2498 | return aops->write_end(file, mapping, pos, len, copied, page, fsdata);
|
| 2499 | }
|
| 2500 | EXPORT_SYMBOL(pagecache_write_end);
|
| 2501 |
|
| 2502 | ssize_t
|
| 2503 | generic_file_direct_write(struct kiocb *iocb, struct iov_iter *from, loff_t pos)
|
| 2504 | {
|
| 2505 | struct file *file = iocb->ki_filp;
|
| 2506 | struct address_space *mapping = file->f_mapping;
|
| 2507 | struct inode *inode = mapping->host;
|
| 2508 | ssize_t written;
|
| 2509 | size_t write_len;
|
| 2510 | pgoff_t end;
|
| 2511 | struct iov_iter data;
|
| 2512 |
|
| 2513 | write_len = iov_iter_count(from);
|
| 2514 | end = (pos + write_len - 1) >> PAGE_SHIFT;
|
| 2515 |
|
| 2516 | written = filemap_write_and_wait_range(mapping, pos, pos + write_len - 1);
|
| 2517 | if (written)
|
| 2518 | goto out;
|
| 2519 |
|
| 2520 | |
| 2521 | * After a write we want buffered reads to be sure to go to disk to get
|
| 2522 | * the new data. We invalidate clean cached page from the region we're
|
| 2523 | * about to write. We do this *before* the write so that we can return
|
| 2524 | * without clobbering -EIOCBQUEUED from ->direct_IO().
|
| 2525 |
|
| 2526 | if (mapping->nrpages) {
|
| 2527 | written = invalidate_inode_pages2_range(mapping,
|
| 2528 | pos >> PAGE_SHIFT, end);
|
| 2529 | |
| 2530 | * If a page can not be invalidated, return 0 to fall back
|
| 2531 | * to buffered write.
|
| 2532 |
|
| 2533 | if (written) {
|
| 2534 | if (written == -EBUSY)
|
| 2535 | return 0;
|
| 2536 | goto out;
|
| 2537 | }
|
| 2538 | }
|
| 2539 |
|
| 2540 | data = *from;
|
| 2541 | written = mapping->a_ops->direct_IO(iocb, &data, pos);
|
| 2542 |
|
| 2543 | |
| 2544 | * Finally, try again to invalidate clean pages which might have been
|
| 2545 | * cached by non-direct readahead, or faulted in by get_user_pages()
|
| 2546 | * if the source of the write was an mmap'ed region of the file
|
| 2547 | * we're writing. Either one is a pretty crazy thing to do,
|
| 2548 | * so we don't support it 100%. If this invalidation
|
| 2549 | * fails, tough, the write still worked...
|
| 2550 |
|
| 2551 | if (mapping->nrpages) {
|
| 2552 | invalidate_inode_pages2_range(mapping,
|
| 2553 | pos >> PAGE_SHIFT, end);
|
| 2554 | }
|
| 2555 |
|
| 2556 | if (written > 0) {
|
| 2557 | pos += written;
|
| 2558 | iov_iter_advance(from, written);
|
| 2559 | if (pos > i_size_read(inode) && !S_ISBLK(inode->i_mode)) {
|
| 2560 | i_size_write(inode, pos);
|
| 2561 | mark_inode_dirty(inode);
|
| 2562 | }
|
| 2563 | iocb->ki_pos = pos;
|
| 2564 | }
|
| 2565 | out:
|
| 2566 | return written;
|
| 2567 | }
|
| 2568 | EXPORT_SYMBOL(generic_file_direct_write);
|
| 2569 |
|
| 2570 | |
| 2571 | * Find or create a page at the given pagecache position. Return the locked
|
| 2572 | * page. This function is specifically for buffered writes.
|
| 2573 |
|
| 2574 | struct page *grab_cache_page_write_begin(struct address_space *mapping,
|
| 2575 | pgoff_t index, unsigned flags)
|
| 2576 | {
|
| 2577 | struct page *page;
|
| 2578 | int fgp_flags = FGP_LOCK|FGP_ACCESSED|FGP_WRITE|FGP_CREAT;
|
| 2579 |
|
| 2580 | if (flags & AOP_FLAG_NOFS)
|
| 2581 | fgp_flags |= FGP_NOFS;
|
| 2582 |
|
| 2583 | page = pagecache_get_page(mapping, index, fgp_flags,
|
| 2584 | mapping_gfp_mask(mapping));
|
| 2585 | if (page)
|
| 2586 | wait_for_stable_page(page);
|
| 2587 |
|
| 2588 | return page;
|
| 2589 | }
|
| 2590 | EXPORT_SYMBOL(grab_cache_page_write_begin);
|
| 2591 |
|
| 2592 | ssize_t generic_perform_write(struct file *file,
|
| 2593 | struct iov_iter *i, loff_t pos)
|
| 2594 | {
|
| 2595 | struct address_space *mapping = file->f_mapping;
|
| 2596 | const struct address_space_operations *a_ops = mapping->a_ops;
|
| 2597 | long status = 0;
|
| 2598 | ssize_t written = 0;
|
| 2599 | unsigned int flags = 0;
|
| 2600 |
|
| 2601 | |
| 2602 | * Copies from kernel address space cannot fail (NFSD is a big user).
|
| 2603 |
|
| 2604 | if (!iter_is_iovec(i))
|
| 2605 | flags |= AOP_FLAG_UNINTERRUPTIBLE;
|
| 2606 |
|
| 2607 | do {
|
| 2608 | struct page *page;
|
| 2609 | unsigned long offset;
|
| 2610 | unsigned long bytes;
|
| 2611 | size_t copied;
|
| 2612 | void *fsdata;
|
| 2613 |
|
| 2614 | offset = (pos & (PAGE_SIZE - 1));
|
| 2615 | bytes = min_t(unsigned long, PAGE_SIZE - offset,
|
| 2616 | iov_iter_count(i));
|
| 2617 |
|
| 2618 | again:
|
| 2619 | |
| 2620 | * Bring in the user page that we will copy from _first_.
|
| 2621 | * Otherwise there's a nasty deadlock on copying from the
|
| 2622 | * same page as we're writing to, without it being marked
|
| 2623 | * up-to-date.
|
| 2624 | *
|
| 2625 | * Not only is this an optimisation, but it is also required
|
| 2626 | * to check that the address is actually valid, when atomic
|
| 2627 | * usercopies are used, below.
|
| 2628 |
|
| 2629 | if (unlikely(iov_iter_fault_in_readable(i, bytes))) {
|
| 2630 | status = -EFAULT;
|
| 2631 | break;
|
| 2632 | }
|
| 2633 |
|
| 2634 | if (fatal_signal_pending(current)) {
|
| 2635 | status = -EINTR;
|
| 2636 | break;
|
| 2637 | }
|
| 2638 |
|
| 2639 | status = a_ops->write_begin(file, mapping, pos, bytes, flags,
|
| 2640 | &page, &fsdata);
|
| 2641 | if (unlikely(status < 0))
|
| 2642 | break;
|
| 2643 |
|
| 2644 | if (mapping_writably_mapped(mapping))
|
| 2645 | flush_dcache_page(page);
|
| 2646 |
|
| 2647 | copied = iov_iter_copy_from_user_atomic(page, i, offset, bytes);
|
| 2648 | flush_dcache_page(page);
|
| 2649 |
|
| 2650 | status = a_ops->write_end(file, mapping, pos, bytes, copied,
|
| 2651 | page, fsdata);
|
| 2652 | if (unlikely(status < 0))
|
| 2653 | break;
|
| 2654 | copied = status;
|
| 2655 |
|
| 2656 | cond_resched();
|
| 2657 |
|
| 2658 | iov_iter_advance(i, copied);
|
| 2659 | if (unlikely(copied == 0)) {
|
| 2660 | |
| 2661 | * If we were unable to copy any data at all, we must
|
| 2662 | * fall back to a single segment length write.
|
| 2663 | *
|
| 2664 | * If we didn't fallback here, we could livelock
|
| 2665 | * because not all segments in the iov can be copied at
|
| 2666 | * once without a pagefault.
|
| 2667 |
|
| 2668 | bytes = min_t(unsigned long, PAGE_SIZE - offset,
|
| 2669 | iov_iter_single_seg_count(i));
|
| 2670 | goto again;
|
| 2671 | }
|
| 2672 | pos += copied;
|
| 2673 | written += copied;
|
| 2674 |
|
| 2675 | balance_dirty_pages_ratelimited(mapping);
|
| 2676 | } while (iov_iter_count(i));
|
| 2677 |
|
| 2678 | return written ? written : status;
|
| 2679 | }
|
| 2680 | EXPORT_SYMBOL(generic_perform_write);
|
| 2681 |
|
| 2682 | |
| 2683 | * __generic_file_write_iter - write data to a file
|
| 2684 | * @iocb: IO state structure (file, offset, etc.)
|
| 2685 | * @from: iov_iter with data to write
|
| 2686 | *
|
| 2687 | * This function does all the work needed for actually writing data to a
|
| 2688 | * file. It does all basic checks, removes SUID from the file, updates
|
| 2689 | * modification times and calls proper subroutines depending on whether we
|
| 2690 | * do direct IO or a standard buffered write.
|
| 2691 | *
|
| 2692 | * It expects i_mutex to be grabbed unless we work on a block device or similar
|
| 2693 | * object which does not need locking at all.
|
| 2694 | *
|
| 2695 | * This function does *not* take care of syncing data in case of O_SYNC write.
|
| 2696 | * A caller has to handle it. This is mainly due to the fact that we want to
|
| 2697 | * avoid syncing under i_mutex.
|
| 2698 |
|
| 2699 | ssize_t __generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
|
| 2700 | {
|
| 2701 | struct file *file = iocb->ki_filp;
|
| 2702 | struct address_space * mapping = file->f_mapping;
|
| 2703 | struct inode *inode = mapping->host;
|
| 2704 | ssize_t written = 0;
|
| 2705 | ssize_t err;
|
| 2706 | ssize_t status;
|
| 2707 |
|
| 2708 |
|
| 2709 | current->backing_dev_info = inode_to_bdi(inode);
|
| 2710 | err = file_remove_privs(file);
|
| 2711 | if (err)
|
| 2712 | goto out;
|
| 2713 |
|
| 2714 | err = file_update_time(file);
|
| 2715 | if (err)
|
| 2716 | goto out;
|
| 2717 |
|
| 2718 | if (iocb->ki_flags & IOCB_DIRECT) {
|
| 2719 | loff_t pos, endbyte;
|
| 2720 |
|
| 2721 | written = generic_file_direct_write(iocb, from, iocb->ki_pos);
|
| 2722 | |
| 2723 | * If the write stopped short of completing, fall back to
|
| 2724 | * buffered writes. Some filesystems do this for writes to
|
| 2725 | * holes, for example. For DAX files, a buffered write will
|
| 2726 | * not succeed (even if it did, DAX does not handle dirty
|
| 2727 | * page-cache pages correctly).
|
| 2728 |
|
| 2729 | if (written < 0 || !iov_iter_count(from) || IS_DAX(inode))
|
| 2730 | goto out;
|
| 2731 |
|
| 2732 | status = generic_perform_write(file, from, pos = iocb->ki_pos);
|
| 2733 | |
| 2734 | * If generic_perform_write() returned a synchronous error
|
| 2735 | * then we want to return the number of bytes which were
|
| 2736 | * direct-written, or the error code if that was zero. Note
|
| 2737 | * that this differs from normal direct-io semantics, which
|
| 2738 | * will return -EFOO even if some bytes were written.
|
| 2739 |
|
| 2740 | if (unlikely(status < 0)) {
|
| 2741 | err = status;
|
| 2742 | goto out;
|
| 2743 | }
|
| 2744 | |
| 2745 | * We need to ensure that the page cache pages are written to
|
| 2746 | * disk and invalidated to preserve the expected O_DIRECT
|
| 2747 | * semantics.
|
| 2748 |
|
| 2749 | endbyte = pos + status - 1;
|
| 2750 | err = filemap_write_and_wait_range(mapping, pos, endbyte);
|
| 2751 | if (err == 0) {
|
| 2752 | iocb->ki_pos = endbyte + 1;
|
| 2753 | written += status;
|
| 2754 | invalidate_mapping_pages(mapping,
|
| 2755 | pos >> PAGE_SHIFT,
|
| 2756 | endbyte >> PAGE_SHIFT);
|
| 2757 | } else {
|
| 2758 | |
| 2759 | * We don't know how much we wrote, so just return
|
| 2760 | * the number of bytes which were direct-written
|
| 2761 |
|
| 2762 | }
|
| 2763 | } else {
|
| 2764 | written = generic_perform_write(file, from, iocb->ki_pos);
|
| 2765 | if (likely(written > 0))
|
| 2766 | iocb->ki_pos += written;
|
| 2767 | }
|
| 2768 | out:
|
| 2769 | current->backing_dev_info = NULL;
|
| 2770 | return written ? written : err;
|
| 2771 | }
|
| 2772 | EXPORT_SYMBOL(__generic_file_write_iter);
|
| 2773 |
|
| 2774 | |
| 2775 | * generic_file_write_iter - write data to a file
|
| 2776 | * @iocb: IO state structure
|
| 2777 | * @from: iov_iter with data to write
|
| 2778 | *
|
| 2779 | * This is a wrapper around __generic_file_write_iter() to be used by most
|
| 2780 | * filesystems. It takes care of syncing the file in case of O_SYNC file
|
| 2781 | * and acquires i_mutex as needed.
|
| 2782 |
|
| 2783 | ssize_t generic_file_write_iter(struct kiocb *iocb, struct iov_iter *from)
|
| 2784 | {
|
| 2785 | struct file *file = iocb->ki_filp;
|
| 2786 | struct inode *inode = file->f_mapping->host;
|
| 2787 | ssize_t ret;
|
| 2788 |
|
| 2789 | inode_lock(inode);
|
| 2790 | ret = generic_write_checks(iocb, from);
|
| 2791 | if (ret > 0)
|
| 2792 | ret = __generic_file_write_iter(iocb, from);
|
| 2793 | inode_unlock(inode);
|
| 2794 |
|
| 2795 | if (ret > 0) {
|
| 2796 | ssize_t err;
|
| 2797 |
|
| 2798 | err = generic_write_sync(file, iocb->ki_pos - ret, ret);
|
| 2799 | if (err < 0)
|
| 2800 | ret = err;
|
| 2801 | }
|
| 2802 | return ret;
|
| 2803 | }
|
| 2804 | EXPORT_SYMBOL(generic_file_write_iter);
|
| 2805 |
|
| 2806 | |
| 2807 | * try_to_release_page() - release old fs-specific metadata on a page
|
| 2808 | *
|
| 2809 | * @page: the page which the kernel is trying to free
|
| 2810 | * @gfp_mask: memory allocation flags (and I/O mode)
|
| 2811 | *
|
| 2812 | * The address_space is to try to release any data against the page
|
| 2813 | * (presumably at page->private). If the release was successful, return `1'.
|
| 2814 | * Otherwise return zero.
|
| 2815 | *
|
| 2816 | * This may also be called if PG_fscache is set on a page, indicating that the
|
| 2817 | * page is known to the local caching routines.
|
| 2818 | *
|
| 2819 | * The @gfp_mask argument specifies whether I/O may be performed to release
|
| 2820 | * this page (__GFP_IO), and whether the call may block (__GFP_RECLAIM & __GFP_FS).
|
| 2821 | *
|
| 2822 |
|
| 2823 | int try_to_release_page(struct page *page, gfp_t gfp_mask)
|
| 2824 | {
|
| 2825 | struct address_space * const mapping = page->mapping;
|
| 2826 |
|
| 2827 | BUG_ON(!PageLocked(page));
|
| 2828 | if (PageWriteback(page))
|
| 2829 | return 0;
|
| 2830 |
|
| 2831 | if (mapping && mapping->a_ops->releasepage)
|
| 2832 | return mapping->a_ops->releasepage(page, gfp_mask);
|
| 2833 | return try_to_free_buffers(page);
|
| 2834 | }
|
| 2835 |
|
| 2836 | EXPORT_SYMBOL(try_to_release_page);
|