1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * mm/fadvise.c 4 * 5 * Copyright (C) 2002, Linus Torvalds 6 * 7 * 11Jan2003 Andrew Morton 8 * 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/pagevec.h> 18 #include <linux/fadvise.h> 19 #include <linux/writeback.h> 20 #include <linux/syscalls.h> 21 #include <linux/swap.h> 22 23 #include <asm/unistd.h> 24 25 #include "internal.h" 26 27 /* 28 * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could 29 * deactivate the pages and clear PG_Referenced. 30 */ 31 32 int generic_fadvise(struct file *file, loff_t offset, loff_t len, int advice) 33 { 34 struct inode *inode; 35 struct address_space *mapping; 36 struct backing_dev_info *bdi; 37 loff_t endbyte; /* inclusive */ 38 pgoff_t start_index; 39 pgoff_t end_index; 40 unsigned long nrpages; 41 42 inode = file_inode(file); 43 if (S_ISFIFO(inode->i_mode)) 44 return -ESPIPE; 45 46 mapping = file->f_mapping; 47 if (!mapping || len < 0) 48 return -EINVAL; 49 50 bdi = inode_to_bdi(mapping->host); 51 52 if (IS_DAX(inode) || (bdi == &noop_backing_dev_info)) { 53 switch (advice) { 54 case POSIX_FADV_NORMAL: 55 case POSIX_FADV_RANDOM: 56 case POSIX_FADV_SEQUENTIAL: 57 case POSIX_FADV_WILLNEED: 58 case POSIX_FADV_NOREUSE: 59 case POSIX_FADV_DONTNEED: 60 /* no bad return value, but ignore advice */ 61 break; 62 default: 63 return -EINVAL; 64 } 65 return 0; 66 } 67 68 /* 69 * Careful about overflows. Len == 0 means "as much as possible". Use 70 * unsigned math because signed overflows are undefined and UBSan 71 * complains. 72 */ 73 endbyte = (u64)offset + (u64)len; 74 if (!len || endbyte < len) 75 endbyte = LLONG_MAX; 76 else 77 endbyte--; /* inclusive */ 78 79 switch (advice) { 80 case POSIX_FADV_NORMAL: 81 file->f_ra.ra_pages = bdi->ra_pages; 82 spin_lock(&file->f_lock); 83 file->f_mode &= ~(FMODE_RANDOM | FMODE_NOREUSE); 84 spin_unlock(&file->f_lock); 85 break; 86 case POSIX_FADV_RANDOM: 87 spin_lock(&file->f_lock); 88 file->f_mode |= FMODE_RANDOM; 89 spin_unlock(&file->f_lock); 90 break; 91 case POSIX_FADV_SEQUENTIAL: 92 file->f_ra.ra_pages = bdi->ra_pages * 2; 93 spin_lock(&file->f_lock); 94 file->f_mode &= ~FMODE_RANDOM; 95 spin_unlock(&file->f_lock); 96 break; 97 case POSIX_FADV_WILLNEED: 98 /* First and last PARTIAL page! */ 99 start_index = offset >> PAGE_SHIFT; 100 end_index = endbyte >> PAGE_SHIFT; 101 102 /* Careful about overflow on the "+1" */ 103 nrpages = end_index - start_index + 1; 104 if (!nrpages) 105 nrpages = ~0UL; 106 107 force_page_cache_readahead(mapping, file, start_index, nrpages); 108 break; 109 case POSIX_FADV_NOREUSE: 110 spin_lock(&file->f_lock); 111 file->f_mode |= FMODE_NOREUSE; 112 spin_unlock(&file->f_lock); 113 break; 114 case POSIX_FADV_DONTNEED: 115 __filemap_fdatawrite_range(mapping, offset, endbyte, 116 WB_SYNC_NONE); 117 118 /* 119 * First and last FULL page! Partial pages are deliberately 120 * preserved on the expectation that it is better to preserve 121 * needed memory than to discard unneeded memory. 122 */ 123 start_index = (offset+(PAGE_SIZE-1)) >> PAGE_SHIFT; 124 end_index = (endbyte >> PAGE_SHIFT); 125 /* 126 * The page at end_index will be inclusively discarded according 127 * by invalidate_mapping_pages(), so subtracting 1 from 128 * end_index means we will skip the last page. But if endbyte 129 * is page aligned or is at the end of file, we should not skip 130 * that page - discarding the last page is safe enough. 131 */ 132 if ((endbyte & ~PAGE_MASK) != ~PAGE_MASK && 133 endbyte != inode->i_size - 1) { 134 /* First page is tricky as 0 - 1 = -1, but pgoff_t 135 * is unsigned, so the end_index >= start_index 136 * check below would be true and we'll discard the whole 137 * file cache which is not what was asked. 138 */ 139 if (end_index == 0) 140 break; 141 142 end_index--; 143 } 144 145 if (end_index >= start_index) { 146 unsigned long nr_pagevec = 0; 147 148 /* 149 * It's common to FADV_DONTNEED right after 150 * the read or write that instantiates the 151 * pages, in which case there will be some 152 * sitting on the local LRU cache. Try to 153 * avoid the expensive remote drain and the 154 * second cache tree walk below by flushing 155 * them out right away. 156 */ 157 lru_add_drain(); 158 159 invalidate_mapping_pagevec(mapping, 160 start_index, end_index, 161 &nr_pagevec); 162 163 /* 164 * If fewer pages were invalidated than expected then 165 * it is possible that some of the pages were on 166 * a per-cpu pagevec for a remote CPU. Drain all 167 * pagevecs and try again. 168 */ 169 if (nr_pagevec) { 170 lru_add_drain_all(); 171 invalidate_mapping_pages(mapping, start_index, 172 end_index); 173 } 174 } 175 break; 176 default: 177 return -EINVAL; 178 } 179 return 0; 180 } 181 EXPORT_SYMBOL(generic_fadvise); 182 183 int vfs_fadvise(struct file *file, loff_t offset, loff_t len, int advice) 184 { 185 if (file->f_op->fadvise) 186 return file->f_op->fadvise(file, offset, len, advice); 187 188 return generic_fadvise(file, offset, len, advice); 189 } 190 EXPORT_SYMBOL(vfs_fadvise); 191 192 #ifdef CONFIG_ADVISE_SYSCALLS 193 194 int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice) 195 { 196 struct fd f = fdget(fd); 197 int ret; 198 199 if (!f.file) 200 return -EBADF; 201 202 ret = vfs_fadvise(f.file, offset, len, advice); 203 204 fdput(f); 205 return ret; 206 } 207 208 SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice) 209 { 210 return ksys_fadvise64_64(fd, offset, len, advice); 211 } 212 213 #ifdef __ARCH_WANT_SYS_FADVISE64 214 215 SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice) 216 { 217 return ksys_fadvise64_64(fd, offset, len, advice); 218 } 219 220 #endif 221 222 #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FADVISE64_64) 223 224 COMPAT_SYSCALL_DEFINE6(fadvise64_64, int, fd, compat_arg_u64_dual(offset), 225 compat_arg_u64_dual(len), int, advice) 226 { 227 return ksys_fadvise64_64(fd, compat_arg_u64_glue(offset), 228 compat_arg_u64_glue(len), advice); 229 } 230 231 #endif 232 #endif 233