blob: 57264d74b8bff0528dd09456c4c81d6c6785363c [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 */
26asmlinkage 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 }
99out:
100 fput(file);
101 return ret;
102}
103
104#ifdef __ARCH_WANT_SYS_FADVISE64
105
106asmlinkage 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