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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 | // SPDX-License-Identifier: GPL-2.0 /* * mm/fadvise.c * * Copyright (C) 2002, Linus Torvalds * * 11Jan2003 Andrew Morton * Initial version. */ #include <linux/kernel.h> #include <linux/file.h> #include <linux/fs.h> #include <linux/mm.h> #include <linux/pagemap.h> #include <linux/backing-dev.h> #include <linux/pagevec.h> #include <linux/fadvise.h> #include <linux/writeback.h> #include <linux/syscalls.h> #include <linux/swap.h> #include <asm/unistd.h> /* * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could * deactivate the pages and clear PG_Referenced. */ SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice) { struct fd f = fdget(fd); struct inode *inode; struct address_space *mapping; struct backing_dev_info *bdi; loff_t endbyte; /* inclusive */ pgoff_t start_index; pgoff_t end_index; unsigned long nrpages; int ret = 0; if (!f.file) return -EBADF; inode = file_inode(f.file); if (S_ISFIFO(inode->i_mode)) { ret = -ESPIPE; goto out; } mapping = f.file->f_mapping; if (!mapping || len < 0) { ret = -EINVAL; goto out; } bdi = inode_to_bdi(mapping->host); if (IS_DAX(inode) || (bdi == &noop_backing_dev_info)) { switch (advice) { case POSIX_FADV_NORMAL: case POSIX_FADV_RANDOM: case POSIX_FADV_SEQUENTIAL: case POSIX_FADV_WILLNEED: case POSIX_FADV_NOREUSE: case POSIX_FADV_DONTNEED: /* no bad return value, but ignore advice */ break; default: ret = -EINVAL; } goto out; } /* * Careful about overflows. Len == 0 means "as much as possible". Use * unsigned math because signed overflows are undefined and UBSan * complains. */ endbyte = (u64)offset + (u64)len; if (!len || endbyte < len) endbyte = -1; else endbyte--; /* inclusive */ switch (advice) { case POSIX_FADV_NORMAL: f.file->f_ra.ra_pages = bdi->ra_pages; spin_lock(&f.file->f_lock); f.file->f_mode &= ~FMODE_RANDOM; spin_unlock(&f.file->f_lock); break; case POSIX_FADV_RANDOM: spin_lock(&f.file->f_lock); f.file->f_mode |= FMODE_RANDOM; spin_unlock(&f.file->f_lock); break; case POSIX_FADV_SEQUENTIAL: f.file->f_ra.ra_pages = bdi->ra_pages * 2; spin_lock(&f.file->f_lock); f.file->f_mode &= ~FMODE_RANDOM; spin_unlock(&f.file->f_lock); break; case POSIX_FADV_WILLNEED: /* First and last PARTIAL page! */ start_index = offset >> PAGE_SHIFT; end_index = endbyte >> PAGE_SHIFT; /* Careful about overflow on the "+1" */ nrpages = end_index - start_index + 1; if (!nrpages) nrpages = ~0UL; /* * Ignore return value because fadvise() shall return * success even if filesystem can't retrieve a hint, */ force_page_cache_readahead(mapping, f.file, start_index, nrpages); break; case POSIX_FADV_NOREUSE: break; case POSIX_FADV_DONTNEED: if (!inode_write_congested(mapping->host)) __filemap_fdatawrite_range(mapping, offset, endbyte, WB_SYNC_NONE); /* * First and last FULL page! Partial pages are deliberately * preserved on the expectation that it is better to preserve * needed memory than to discard unneeded memory. */ start_index = (offset+(PAGE_SIZE-1)) >> PAGE_SHIFT; end_index = (endbyte >> PAGE_SHIFT); /* * The page at end_index will be inclusively discarded according * by invalidate_mapping_pages(), so subtracting 1 from * end_index means we will skip the last page. But if endbyte * is page aligned or is at the end of file, we should not skip * that page - discarding the last page is safe enough. */ if ((endbyte & ~PAGE_MASK) != ~PAGE_MASK && endbyte != inode->i_size - 1) { /* First page is tricky as 0 - 1 = -1, but pgoff_t * is unsigned, so the end_index >= start_index * check below would be true and we'll discard the whole * file cache which is not what was asked. */ if (end_index == 0) break; end_index--; } if (end_index >= start_index) { unsigned long count; /* * It's common to FADV_DONTNEED right after * the read or write that instantiates the * pages, in which case there will be some * sitting on the local LRU cache. Try to * avoid the expensive remote drain and the * second cache tree walk below by flushing * them out right away. */ lru_add_drain(); count = invalidate_mapping_pages(mapping, start_index, end_index); /* * If fewer pages were invalidated than expected then * it is possible that some of the pages were on * a per-cpu pagevec for a remote CPU. Drain all * pagevecs and try again. */ if (count < (end_index - start_index + 1)) { lru_add_drain_all(); invalidate_mapping_pages(mapping, start_index, end_index); } } break; default: ret = -EINVAL; } out: fdput(f); return ret; } #ifdef __ARCH_WANT_SYS_FADVISE64 SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice) { return sys_fadvise64_64(fd, offset, len, advice); } #endif |