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1// SPDX-License-Identifier: GPL-2.02/*3 * mm/fadvise.c4 *5 * Copyright (C) 2002, Linus Torvalds6 *7 * 11Jan2003 Andrew Morton8 * Initial version.9 */10 11#include <linux/kernel.h>12#include <linux/file.h>13#include <linux/fs.h>14#include <linux/mm.h>15#include <linux/pagemap.h>16#include <linux/backing-dev.h>17#include <linux/fadvise.h>18#include <linux/writeback.h>19#include <linux/syscalls.h>20#include <linux/swap.h>21 22#include <asm/unistd.h>23 24#include "internal.h"25 26/*27 * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could28 * deactivate the pages and clear PG_Referenced.29 */30 31int generic_fadvise(struct file *file, loff_t offset, loff_t len, int advice)32{33 struct inode *inode;34 struct address_space *mapping;35 struct backing_dev_info *bdi;36 loff_t endbyte; /* inclusive */37 pgoff_t start_index;38 pgoff_t end_index;39 unsigned long nrpages;40 41 inode = file_inode(file);42 if (S_ISFIFO(inode->i_mode))43 return -ESPIPE;44 45 mapping = file->f_mapping;46 if (!mapping || len < 0)47 return -EINVAL;48 49 bdi = inode_to_bdi(mapping->host);50 51 if (IS_DAX(inode) || (bdi == &noop_backing_dev_info)) {52 switch (advice) {53 case POSIX_FADV_NORMAL:54 case POSIX_FADV_RANDOM:55 case POSIX_FADV_SEQUENTIAL:56 case POSIX_FADV_WILLNEED:57 case POSIX_FADV_NOREUSE:58 case POSIX_FADV_DONTNEED:59 /* no bad return value, but ignore advice */60 break;61 default:62 return -EINVAL;63 }64 return 0;65 }66 67 /*68 * Careful about overflows. Len == 0 means "as much as possible". Use69 * unsigned math because signed overflows are undefined and UBSan70 * complains.71 */72 endbyte = (u64)offset + (u64)len;73 if (!len || endbyte < len)74 endbyte = LLONG_MAX;75 else76 endbyte--; /* inclusive */77 78 switch (advice) {79 case POSIX_FADV_NORMAL:80 file->f_ra.ra_pages = bdi->ra_pages;81 spin_lock(&file->f_lock);82 file->f_mode &= ~(FMODE_RANDOM | FMODE_NOREUSE);83 spin_unlock(&file->f_lock);84 break;85 case POSIX_FADV_RANDOM:86 spin_lock(&file->f_lock);87 file->f_mode |= FMODE_RANDOM;88 spin_unlock(&file->f_lock);89 break;90 case POSIX_FADV_SEQUENTIAL:91 file->f_ra.ra_pages = bdi->ra_pages * 2;92 spin_lock(&file->f_lock);93 file->f_mode &= ~FMODE_RANDOM;94 spin_unlock(&file->f_lock);95 break;96 case POSIX_FADV_WILLNEED:97 /* First and last PARTIAL page! */98 start_index = offset >> PAGE_SHIFT;99 end_index = endbyte >> PAGE_SHIFT;100 101 /* Careful about overflow on the "+1" */102 nrpages = end_index - start_index + 1;103 if (!nrpages)104 nrpages = ~0UL;105 106 force_page_cache_readahead(mapping, file, start_index, nrpages);107 break;108 case POSIX_FADV_NOREUSE:109 spin_lock(&file->f_lock);110 file->f_mode |= FMODE_NOREUSE;111 spin_unlock(&file->f_lock);112 break;113 case POSIX_FADV_DONTNEED:114 __filemap_fdatawrite_range(mapping, offset, endbyte,115 WB_SYNC_NONE);116 117 /*118 * First and last FULL page! Partial pages are deliberately119 * preserved on the expectation that it is better to preserve120 * needed memory than to discard unneeded memory.121 */122 start_index = (offset+(PAGE_SIZE-1)) >> PAGE_SHIFT;123 end_index = (endbyte >> PAGE_SHIFT);124 /*125 * The page at end_index will be inclusively discarded according126 * by invalidate_mapping_pages(), so subtracting 1 from127 * end_index means we will skip the last page. But if endbyte128 * is page aligned or is at the end of file, we should not skip129 * that page - discarding the last page is safe enough.130 */131 if ((endbyte & ~PAGE_MASK) != ~PAGE_MASK &&132 endbyte != inode->i_size - 1) {133 /* First page is tricky as 0 - 1 = -1, but pgoff_t134 * is unsigned, so the end_index >= start_index135 * check below would be true and we'll discard the whole136 * file cache which is not what was asked.137 */138 if (end_index == 0)139 break;140 141 end_index--;142 }143 144 if (end_index >= start_index) {145 unsigned long nr_failed = 0;146 147 /*148 * It's common to FADV_DONTNEED right after149 * the read or write that instantiates the150 * pages, in which case there will be some151 * sitting on the local LRU cache. Try to152 * avoid the expensive remote drain and the153 * second cache tree walk below by flushing154 * them out right away.155 */156 lru_add_drain();157 158 mapping_try_invalidate(mapping, start_index, end_index,159 &nr_failed);160 161 /*162 * The failures may be due to the folio being163 * in the LRU cache of a remote CPU. Drain all164 * caches and try again.165 */166 if (nr_failed) {167 lru_add_drain_all();168 invalidate_mapping_pages(mapping, start_index,169 end_index);170 }171 }172 break;173 default:174 return -EINVAL;175 }176 return 0;177}178EXPORT_SYMBOL(generic_fadvise);179 180int vfs_fadvise(struct file *file, loff_t offset, loff_t len, int advice)181{182 if (file->f_op->fadvise)183 return file->f_op->fadvise(file, offset, len, advice);184 185 return generic_fadvise(file, offset, len, advice);186}187EXPORT_SYMBOL(vfs_fadvise);188 189#ifdef CONFIG_ADVISE_SYSCALLS190 191int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)192{193 struct fd f = fdget(fd);194 int ret;195 196 if (!fd_file(f))197 return -EBADF;198 199 ret = vfs_fadvise(fd_file(f), offset, len, advice);200 201 fdput(f);202 return ret;203}204 205SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)206{207 return ksys_fadvise64_64(fd, offset, len, advice);208}209 210#ifdef __ARCH_WANT_SYS_FADVISE64211 212SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)213{214 return ksys_fadvise64_64(fd, offset, len, advice);215}216 217#endif218 219#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FADVISE64_64)220 221COMPAT_SYSCALL_DEFINE6(fadvise64_64, int, fd, compat_arg_u64_dual(offset),222 compat_arg_u64_dual(len), int, advice)223{224 return ksys_fadvise64_64(fd, compat_arg_u64_glue(offset),225 compat_arg_u64_glue(len), advice);226}227 228#endif229#endif230