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gerrit-public.fairphone.software / kernel / msm-4.9 / 63bea35036540c0e8a309aef9bc37a9acfb520ae / . / mm / fadvise.c
blob: 5f19e87bc5af1c86dd121d7e50dcd3e5cc1c7e94 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 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 */
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
Carsten Ottefe77ba62005-06-23 22:05:29 -0700[diff] [blame]46 if (mapping->a_ops->get_xip_page)
47 /* no bad return value, but ignore advice */
48 goto out;
49
Linus Torvalds1da177e2005-04-16 15:20:36 -0700[diff] [blame]50 /* Careful about overflows. Len == 0 means "as much as possible" */
51 endbyte = offset + len;
52 if (!len || endbyte < len)
53 endbyte = -1;
54
55 bdi = mapping->backing_dev_info;
56
57 switch (advice) {
58 case POSIX_FADV_NORMAL:
59 file->f_ra.ra_pages = bdi->ra_pages;
60 break;
61 case POSIX_FADV_RANDOM:
62 file->f_ra.ra_pages = 0;
63 break;
64 case POSIX_FADV_SEQUENTIAL:
65 file->f_ra.ra_pages = bdi->ra_pages * 2;
66 break;
67 case POSIX_FADV_WILLNEED:
68 case POSIX_FADV_NOREUSE:
69 if (!mapping->a_ops->readpage) {
70 ret = -EINVAL;
71 break;
72 }
73
74 /* First and last PARTIAL page! */
75 start_index = offset >> PAGE_CACHE_SHIFT;
76 end_index = (endbyte-1) >> PAGE_CACHE_SHIFT;
77
78 /* Careful about overflow on the "+1" */
79 nrpages = end_index - start_index + 1;
80 if (!nrpages)
81 nrpages = ~0UL;
82
83 ret = force_page_cache_readahead(mapping, file,
84 start_index,
85 max_sane_readahead(nrpages));
86 if (ret > 0)
87 ret = 0;
88 break;
89 case POSIX_FADV_DONTNEED:
90 if (!bdi_write_congested(mapping->backing_dev_info))
91 filemap_flush(mapping);
92
93 /* First and last FULL page! */
94 start_index = (offset + (PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
95 end_index = (endbyte >> PAGE_CACHE_SHIFT);
96
97 if (end_index > start_index)
98 invalidate_mapping_pages(mapping, start_index, end_index-1);
99 break;
100 default:
101 ret = -EINVAL;
102 }
103out:
104 fput(file);
105 return ret;
106}
107
108#ifdef __ARCH_WANT_SYS_FADVISE64
109
110asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice)
111{
112 return sys_fadvise64_64(fd, offset, len, advice);
113}
114
115#endif