| 1 | /* |
| 2 | * mm/fadvise.c |
| 3 | * |
| 4 | * Copyright (C) 2002, Linus Torvalds |
| 5 | * |
| 6 | * 11Jan2003 Andrew Morton |
| 7 | * Initial version. |
| 8 | */ |
| 9 | |
| 10 | #include <linux/kernel.h> |
| 11 | #include <linux/file.h> |
| 12 | #include <linux/fs.h> |
| 13 | #include <linux/mm.h> |
| 14 | #include <linux/pagemap.h> |
| 15 | #include <linux/backing-dev.h> |
| 16 | #include <linux/pagevec.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 | /* |
| 25 | * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could |
| 26 | * deactivate the pages and clear PG_Referenced. |
| 27 | */ |
| 28 | SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice) |
| 29 | { |
| 30 | struct fd f = fdget(fd); |
| 31 | struct inode *inode; |
| 32 | struct address_space *mapping; |
| 33 | struct backing_dev_info *bdi; |
| 34 | loff_t endbyte; /* inclusive */ |
| 35 | pgoff_t start_index; |
| 36 | pgoff_t end_index; |
| 37 | unsigned long nrpages; |
| 38 | int ret = 0; |
| 39 | |
| 40 | if (!f.file) |
| 41 | return -EBADF; |
| 42 | |
| 43 | inode = file_inode(f.file); |
| 44 | if (S_ISFIFO(inode->i_mode)) { |
| 45 | ret = -ESPIPE; |
| 46 | goto out; |
| 47 | } |
| 48 | |
| 49 | mapping = f.file->f_mapping; |
| 50 | if (!mapping || len < 0) { |
| 51 | ret = -EINVAL; |
| 52 | goto out; |
| 53 | } |
| 54 | |
| 55 | if (IS_DAX(inode)) { |
| 56 | switch (advice) { |
| 57 | case POSIX_FADV_NORMAL: |
| 58 | case POSIX_FADV_RANDOM: |
| 59 | case POSIX_FADV_SEQUENTIAL: |
| 60 | case POSIX_FADV_WILLNEED: |
| 61 | case POSIX_FADV_NOREUSE: |
| 62 | case POSIX_FADV_DONTNEED: |
| 63 | /* no bad return value, but ignore advice */ |
| 64 | break; |
| 65 | default: |
| 66 | ret = -EINVAL; |
| 67 | } |
| 68 | goto out; |
| 69 | } |
| 70 | |
| 71 | /* Careful about overflows. Len == 0 means "as much as possible" */ |
| 72 | endbyte = offset + len; |
| 73 | if (!len || endbyte < len) |
| 74 | endbyte = -1; |
| 75 | else |
| 76 | endbyte--; /* inclusive */ |
| 77 | |
| 78 | bdi = inode_to_bdi(mapping->host); |
| 79 | |
| 80 | switch (advice) { |
| 81 | case POSIX_FADV_NORMAL: |
| 82 | f.file->f_ra.ra_pages = bdi->ra_pages; |
| 83 | spin_lock(&f.file->f_lock); |
| 84 | f.file->f_mode &= ~FMODE_RANDOM; |
| 85 | spin_unlock(&f.file->f_lock); |
| 86 | break; |
| 87 | case POSIX_FADV_RANDOM: |
| 88 | spin_lock(&f.file->f_lock); |
| 89 | f.file->f_mode |= FMODE_RANDOM; |
| 90 | spin_unlock(&f.file->f_lock); |
| 91 | break; |
| 92 | case POSIX_FADV_SEQUENTIAL: |
| 93 | f.file->f_ra.ra_pages = bdi->ra_pages * 2; |
| 94 | spin_lock(&f.file->f_lock); |
| 95 | f.file->f_mode &= ~FMODE_RANDOM; |
| 96 | spin_unlock(&f.file->f_lock); |
| 97 | break; |
| 98 | case POSIX_FADV_WILLNEED: |
| 99 | /* First and last PARTIAL page! */ |
| 100 | start_index = offset >> PAGE_SHIFT; |
| 101 | end_index = endbyte >> PAGE_SHIFT; |
| 102 | |
| 103 | /* Careful about overflow on the "+1" */ |
| 104 | nrpages = end_index - start_index + 1; |
| 105 | if (!nrpages) |
| 106 | nrpages = ~0UL; |
| 107 | |
| 108 | /* |
| 109 | * Ignore return value because fadvise() shall return |
| 110 | * success even if filesystem can't retrieve a hint, |
| 111 | */ |
| 112 | force_page_cache_readahead(mapping, f.file, start_index, |
| 113 | nrpages); |
| 114 | break; |
| 115 | case POSIX_FADV_NOREUSE: |
| 116 | break; |
| 117 | case POSIX_FADV_DONTNEED: |
| 118 | if (!inode_write_congested(mapping->host)) |
| 119 | __filemap_fdatawrite_range(mapping, offset, endbyte, |
| 120 | WB_SYNC_NONE); |
| 121 | |
| 122 | /* |
| 123 | * First and last FULL page! Partial pages are deliberately |
| 124 | * preserved on the expectation that it is better to preserve |
| 125 | * needed memory than to discard unneeded memory. |
| 126 | */ |
| 127 | start_index = (offset+(PAGE_SIZE-1)) >> PAGE_SHIFT; |
| 128 | end_index = (endbyte >> PAGE_SHIFT); |
| 129 | if ((endbyte & ~PAGE_MASK) != ~PAGE_MASK) { |
| 130 | /* First page is tricky as 0 - 1 = -1, but pgoff_t |
| 131 | * is unsigned, so the end_index >= start_index |
| 132 | * check below would be true and we'll discard the whole |
| 133 | * file cache which is not what was asked. |
| 134 | */ |
| 135 | if (end_index == 0) |
| 136 | break; |
| 137 | |
| 138 | end_index--; |
| 139 | } |
| 140 | |
| 141 | if (end_index >= start_index) { |
| 142 | unsigned long count = invalidate_mapping_pages(mapping, |
| 143 | start_index, end_index); |
| 144 | |
| 145 | /* |
| 146 | * If fewer pages were invalidated than expected then |
| 147 | * it is possible that some of the pages were on |
| 148 | * a per-cpu pagevec for a remote CPU. Drain all |
| 149 | * pagevecs and try again. |
| 150 | */ |
| 151 | if (count < (end_index - start_index + 1)) { |
| 152 | lru_add_drain_all(); |
| 153 | invalidate_mapping_pages(mapping, start_index, |
| 154 | end_index); |
| 155 | } |
| 156 | } |
| 157 | break; |
| 158 | default: |
| 159 | ret = -EINVAL; |
| 160 | } |
| 161 | out: |
| 162 | fdput(f); |
| 163 | return ret; |
| 164 | } |
| 165 | |
| 166 | #ifdef __ARCH_WANT_SYS_FADVISE64 |
| 167 | |
| 168 | SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice) |
| 169 | { |
| 170 | return sys_fadvise64_64(fd, offset, len, advice); |
| 171 | } |
| 172 | |
| 173 | #endif |