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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 if (S_ISFIFO(file->f_dentry->d_inode->i_mode)) {
41 ret = -ESPIPE;
42 goto out;
43 }
44
45 mapping = file->f_mapping;
46 if (!mapping || len < 0) {
47 ret = -EINVAL;
48 goto out;
49 }
50
51 if (mapping->a_ops->get_xip_page)
52 /* no bad return value, but ignore advice */
53 goto out;
54
55 /* Careful about overflows. Len == 0 means "as much as possible" */
56 endbyte = offset + len;
57 if (!len || endbyte < len)
58 endbyte = -1;
59
60 bdi = mapping->backing_dev_info;
61
62 switch (advice) {
63 case POSIX_FADV_NORMAL:
64 file->f_ra.ra_pages = bdi->ra_pages;
65 break;
66 case POSIX_FADV_RANDOM:
67 file->f_ra.ra_pages = 0;
68 break;
69 case POSIX_FADV_SEQUENTIAL:
70 file->f_ra.ra_pages = bdi->ra_pages * 2;
71 break;
72 case POSIX_FADV_WILLNEED:
73 case POSIX_FADV_NOREUSE:
74 if (!mapping->a_ops->readpage) {
75 ret = -EINVAL;
76 break;
77 }
78
79 /* First and last PARTIAL page! */
80 start_index = offset >> PAGE_CACHE_SHIFT;
81 end_index = (endbyte-1) >> PAGE_CACHE_SHIFT;
82
83 /* Careful about overflow on the "+1" */
84 nrpages = end_index - start_index + 1;
85 if (!nrpages)
86 nrpages = ~0UL;
87
88 ret = force_page_cache_readahead(mapping, file,
89 start_index,
90 max_sane_readahead(nrpages));
91 if (ret > 0)
92 ret = 0;
93 break;
94 case POSIX_FADV_DONTNEED:
95 if (!bdi_write_congested(mapping->backing_dev_info))
96 filemap_flush(mapping);
97
98 /* First and last FULL page! */
99 start_index = (offset + (PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
100 end_index = (endbyte >> PAGE_CACHE_SHIFT);
101
102 if (end_index > start_index)
103 invalidate_mapping_pages(mapping, start_index, end_index-1);
104 break;
105 default:
106 ret = -EINVAL;
107 }
108 out:
109 fput(file);
110 return ret;
111 }
112
113 #ifdef __ARCH_WANT_SYS_FADVISE64
114
115 asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice)
116 {
117 return sys_fadvise64_64(fd, offset, len, advice);
118 }
119
120 #endif