[PATCH] swsusp: move snapshot functionality to separate file
[linux-2.6.git] / mm / fadvise.c
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         if (mapping->a_ops->get_xip_page)
47                 /* no bad return value, but ignore advice */
48                 goto out;
49
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         }
103 out:
104         fput(file);
105         return ret;
106 }
107
108 #ifdef __ARCH_WANT_SYS_FADVISE64
109
110 asmlinkage 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