[PATCH] sys_sync_file_range()
[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  * LINUX_FADV_ASYNC_WRITE: start async writeout of any dirty pages between file
28  * offsets `offset' and `offset+len' inclusive.  Any pages which are currently
29  * under writeout are skipped, whether or not they are dirty.
30  *
31  * LINUX_FADV_WRITE_WAIT: wait upon writeout of any dirty pages between file
32  * offsets `offset' and `offset+len'.
33  *
34  * By combining these two operations the application may do several things:
35  *
36  * LINUX_FADV_ASYNC_WRITE: push some or all of the dirty pages at the disk.
37  *
38  */
39 asmlinkage long sys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
40 {
41         struct file *file = fget(fd);
42         struct address_space *mapping;
43         struct backing_dev_info *bdi;
44         loff_t endbyte;                 /* inclusive */
45         pgoff_t start_index;
46         pgoff_t end_index;
47         unsigned long nrpages;
48         int ret = 0;
49
50         if (!file)
51                 return -EBADF;
52
53         if (S_ISFIFO(file->f_dentry->d_inode->i_mode)) {
54                 ret = -ESPIPE;
55                 goto out;
56         }
57
58         mapping = file->f_mapping;
59         if (!mapping || len < 0) {
60                 ret = -EINVAL;
61                 goto out;
62         }
63
64         if (mapping->a_ops->get_xip_page)
65                 /* no bad return value, but ignore advice */
66                 goto out;
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         case POSIX_FADV_NOREUSE:
89                 if (!mapping->a_ops->readpage) {
90                         ret = -EINVAL;
91                         break;
92                 }
93
94                 /* First and last PARTIAL page! */
95                 start_index = offset >> PAGE_CACHE_SHIFT;
96                 end_index = endbyte >> PAGE_CACHE_SHIFT;
97
98                 /* Careful about overflow on the "+1" */
99                 nrpages = end_index - start_index + 1;
100                 if (!nrpages)
101                         nrpages = ~0UL;
102                 
103                 ret = force_page_cache_readahead(mapping, file,
104                                 start_index,
105                                 max_sane_readahead(nrpages));
106                 if (ret > 0)
107                         ret = 0;
108                 break;
109         case POSIX_FADV_DONTNEED:
110                 if (!bdi_write_congested(mapping->backing_dev_info))
111                         filemap_flush(mapping);
112
113                 /* First and last FULL page! */
114                 start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
115                 end_index = (endbyte >> PAGE_CACHE_SHIFT);
116
117                 if (end_index >= start_index)
118                         invalidate_mapping_pages(mapping, start_index,
119                                                 end_index);
120                 break;
121         default:
122                 ret = -EINVAL;
123         }
124 out:
125         fput(file);
126         return ret;
127 }
128
129 #ifdef __ARCH_WANT_SYS_FADVISE64
130
131 asmlinkage long sys_fadvise64(int fd, loff_t offset, size_t len, int advice)
132 {
133         return sys_fadvise64_64(fd, offset, len, advice);
134 }
135
136 #endif