[PATCH] sparsemem swiss cheese numa layouts
[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         /* 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