[SCSI] tmscsim: Further clean-up of the driver
[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_page)
53                 /* no bad return value, but ignore advice */
54                 goto out;
55
56         /* Careful about overflows. Len == 0 means "as much as possible" */
57         endbyte = offset + len;
58         if (!len || endbyte < len)
59                 endbyte = -1;
60         else
61                 endbyte--;              /* inclusive */
62
63         bdi = mapping->backing_dev_info;
64
65         switch (advice) {
66         case POSIX_FADV_NORMAL:
67                 file->f_ra.ra_pages = bdi->ra_pages;
68                 break;
69         case POSIX_FADV_RANDOM:
70                 file->f_ra.ra_pages = 0;
71                 break;
72         case POSIX_FADV_SEQUENTIAL:
73                 file->f_ra.ra_pages = bdi->ra_pages * 2;
74                 break;
75         case POSIX_FADV_WILLNEED:
76                 if (!mapping->a_ops->readpage) {
77                         ret = -EINVAL;
78                         break;
79                 }
80
81                 /* First and last PARTIAL page! */
82                 start_index = offset >> PAGE_CACHE_SHIFT;
83                 end_index = endbyte >> PAGE_CACHE_SHIFT;
84
85                 /* Careful about overflow on the "+1" */
86                 nrpages = end_index - start_index + 1;
87                 if (!nrpages)
88                         nrpages = ~0UL;
89                 
90                 ret = force_page_cache_readahead(mapping, file,
91                                 start_index,
92                                 max_sane_readahead(nrpages));
93                 if (ret > 0)
94                         ret = 0;
95                 break;
96         case POSIX_FADV_NOREUSE:
97                 break;
98         case POSIX_FADV_DONTNEED:
99                 if (!bdi_write_congested(mapping->backing_dev_info))
100                         filemap_flush(mapping);
101
102                 /* First and last FULL page! */
103                 start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
104                 end_index = (endbyte >> PAGE_CACHE_SHIFT);
105
106                 if (end_index >= start_index)
107                         invalidate_mapping_pages(mapping, start_index,
108                                                 end_index);
109                 break;
110         default:
111                 ret = -EINVAL;
112         }
113 out:
114         fput(file);
115         return ret;
116 }
117
118 #ifdef __ARCH_WANT_SYS_FADVISE64
119
120 asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice)
121 {
122         return sys_fadvise64_64(fd, offset, len, advice);
123 }
124
125 #endif