| Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | * mm/fadvise.c |
| 3 | * |
| 4 | * Copyright (C) 2002, Linus Torvalds |
| 5 | * |
| 6 | * 11Jan2003 akpm@digeo.com |
| 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/syscalls.h> |
| 19 | |
| 20 | #include <asm/unistd.h> |
| 21 | |
| 22 | /* |
| 23 | * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could |
| 24 | * deactivate the pages and clear PG_Referenced. |
| 25 | */ |
| 26 | asmlinkage long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice) |
| 27 | { |
| 28 | struct file *file = fget(fd); |
| 29 | struct address_space *mapping; |
| 30 | struct backing_dev_info *bdi; |
| 31 | loff_t endbyte; |
| 32 | pgoff_t start_index; |
| 33 | pgoff_t end_index; |
| 34 | unsigned long nrpages; |
| 35 | int ret = 0; |
| 36 | |
| 37 | if (!file) |
| 38 | return -EBADF; |
| 39 | |
| 40 | mapping = file->f_mapping; |
| 41 | if (!mapping || len < 0) { |
| 42 | ret = -EINVAL; |
| 43 | goto out; |
| 44 | } |
| 45 | |
| 46 | /* Careful about overflows. Len == 0 means "as much as possible" */ |
| 47 | endbyte = offset + len; |
| 48 | if (!len || endbyte < len) |
| 49 | endbyte = -1; |
| 50 | |
| 51 | bdi = mapping->backing_dev_info; |
| 52 | |
| 53 | switch (advice) { |
| 54 | case POSIX_FADV_NORMAL: |
| 55 | file->f_ra.ra_pages = bdi->ra_pages; |
| 56 | break; |
| 57 | case POSIX_FADV_RANDOM: |
| 58 | file->f_ra.ra_pages = 0; |
| 59 | break; |
| 60 | case POSIX_FADV_SEQUENTIAL: |
| 61 | file->f_ra.ra_pages = bdi->ra_pages * 2; |
| 62 | break; |
| 63 | case POSIX_FADV_WILLNEED: |
| 64 | case POSIX_FADV_NOREUSE: |
| 65 | if (!mapping->a_ops->readpage) { |
| 66 | ret = -EINVAL; |
| 67 | break; |
| 68 | } |
| 69 | |
| 70 | /* First and last PARTIAL page! */ |
| 71 | start_index = offset >> PAGE_CACHE_SHIFT; |
| 72 | end_index = (endbyte-1) >> PAGE_CACHE_SHIFT; |
| 73 | |
| 74 | /* Careful about overflow on the "+1" */ |
| 75 | nrpages = end_index - start_index + 1; |
| 76 | if (!nrpages) |
| 77 | nrpages = ~0UL; |
| 78 | |
| 79 | ret = force_page_cache_readahead(mapping, file, |
| 80 | start_index, |
| 81 | max_sane_readahead(nrpages)); |
| 82 | if (ret > 0) |
| 83 | ret = 0; |
| 84 | break; |
| 85 | case POSIX_FADV_DONTNEED: |
| 86 | if (!bdi_write_congested(mapping->backing_dev_info)) |
| 87 | filemap_flush(mapping); |
| 88 | |
| 89 | /* First and last FULL page! */ |
| 90 | start_index = (offset + (PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT; |
| 91 | end_index = (endbyte >> PAGE_CACHE_SHIFT); |
| 92 | |
| 93 | if (end_index > start_index) |
| 94 | invalidate_mapping_pages(mapping, start_index, end_index-1); |
| 95 | break; |
| 96 | default: |
| 97 | ret = -EINVAL; |
| 98 | } |
| 99 | out: |
| 100 | fput(file); |
| 101 | return ret; |
| 102 | } |
| 103 | |
| 104 | #ifdef __ARCH_WANT_SYS_FADVISE64 |
| 105 | |
| 106 | asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice) |
| 107 | { |
| 108 | return sys_fadvise64_64(fd, offset, len, advice); |
| 109 | } |
| 110 | |
| 111 | #endif |