nommu: Provide vmalloc_exec().
[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/writeback.h>
19 #include <linux/syscalls.h>
20
21 #include <asm/unistd.h>
22
23 /*
24  * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
25  * deactivate the pages and clear PG_Referenced.
26  */
27 asmlinkage long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
28 {
29         struct file *file = fget(fd);
30         struct address_space *mapping;
31         struct backing_dev_info *bdi;
32         loff_t endbyte;                 /* inclusive */
33         pgoff_t start_index;
34         pgoff_t end_index;
35         unsigned long nrpages;
36         int ret = 0;
37
38         if (!file)
39                 return -EBADF;
40
41         if (S_ISFIFO(file->f_path.dentry->d_inode->i_mode)) {
42                 ret = -ESPIPE;
43                 goto out;
44         }
45
46         mapping = file->f_mapping;
47         if (!mapping || len < 0) {
48                 ret = -EINVAL;
49                 goto out;
50         }
51
52         if (mapping->a_ops->get_xip_mem) {
53                 switch (advice) {
54                 case POSIX_FADV_NORMAL:
55                 case POSIX_FADV_RANDOM:
56                 case POSIX_FADV_SEQUENTIAL:
57                 case POSIX_FADV_WILLNEED:
58                 case POSIX_FADV_NOREUSE:
59                 case POSIX_FADV_DONTNEED:
60                         /* no bad return value, but ignore advice */
61                         break;
62                 default:
63                         ret = -EINVAL;
64                 }
65                 goto out;
66         }
67
68         /* Careful about overflows. Len == 0 means "as much as possible" */
69         endbyte = offset + len;
70         if (!len || endbyte < len)
71                 endbyte = -1;
72         else
73                 endbyte--;              /* inclusive */
74
75         bdi = mapping->backing_dev_info;
76
77         switch (advice) {
78         case POSIX_FADV_NORMAL:
79                 file->f_ra.ra_pages = bdi->ra_pages;
80                 break;
81         case POSIX_FADV_RANDOM:
82                 file->f_ra.ra_pages = 0;
83                 break;
84         case POSIX_FADV_SEQUENTIAL:
85                 file->f_ra.ra_pages = bdi->ra_pages * 2;
86                 break;
87         case POSIX_FADV_WILLNEED:
88                 if (!mapping->a_ops->readpage) {
89                         ret = -EINVAL;
90                         break;
91                 }
92
93                 /* First and last PARTIAL page! */
94                 start_index = offset >> PAGE_CACHE_SHIFT;
95                 end_index = endbyte >> PAGE_CACHE_SHIFT;
96
97                 /* Careful about overflow on the "+1" */
98                 nrpages = end_index - start_index + 1;
99                 if (!nrpages)
100                         nrpages = ~0UL;
101                 
102                 ret = force_page_cache_readahead(mapping, file,
103                                 start_index,
104                                 max_sane_readahead(nrpages));
105                 if (ret > 0)
106                         ret = 0;
107                 break;
108         case POSIX_FADV_NOREUSE:
109                 break;
110         case POSIX_FADV_DONTNEED:
111                 if (!bdi_write_congested(mapping->backing_dev_info))
112                         filemap_flush(mapping);
113
114                 /* First and last FULL page! */
115                 start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
116                 end_index = (endbyte >> PAGE_CACHE_SHIFT);
117
118                 if (end_index >= start_index)
119                         invalidate_mapping_pages(mapping, start_index,
120                                                 end_index);
121                 break;
122         default:
123                 ret = -EINVAL;
124         }
125 out:
126         fput(file);
127         return ret;
128 }
129
130 #ifdef __ARCH_WANT_SYS_FADVISE64
131
132 asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice)
133 {
134         return sys_fadvise64_64(fd, offset, len, advice);
135 }
136
137 #endif