mm: mmu_notifier: have mmu_notifiers use a global SRCU so they may safely schedule
[linux-2.6.git] / mm / fadvise.c
1 /*
2  * mm/fadvise.c
3  *
4  * Copyright (C) 2002, Linus Torvalds
5  *
6  * 11Jan2003    Andrew Morton
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 SYSCALL_DEFINE(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                 spin_lock(&file->f_lock);
81                 file->f_mode &= ~FMODE_RANDOM;
82                 spin_unlock(&file->f_lock);
83                 break;
84         case POSIX_FADV_RANDOM:
85                 spin_lock(&file->f_lock);
86                 file->f_mode |= FMODE_RANDOM;
87                 spin_unlock(&file->f_lock);
88                 break;
89         case POSIX_FADV_SEQUENTIAL:
90                 file->f_ra.ra_pages = bdi->ra_pages * 2;
91                 spin_lock(&file->f_lock);
92                 file->f_mode &= ~FMODE_RANDOM;
93                 spin_unlock(&file->f_lock);
94                 break;
95         case POSIX_FADV_WILLNEED:
96                 if (!mapping->a_ops->readpage) {
97                         ret = -EINVAL;
98                         break;
99                 }
100
101                 /* First and last PARTIAL page! */
102                 start_index = offset >> PAGE_CACHE_SHIFT;
103                 end_index = endbyte >> PAGE_CACHE_SHIFT;
104
105                 /* Careful about overflow on the "+1" */
106                 nrpages = end_index - start_index + 1;
107                 if (!nrpages)
108                         nrpages = ~0UL;
109                 
110                 ret = force_page_cache_readahead(mapping, file,
111                                 start_index,
112                                 nrpages);
113                 if (ret > 0)
114                         ret = 0;
115                 break;
116         case POSIX_FADV_NOREUSE:
117                 break;
118         case POSIX_FADV_DONTNEED:
119                 if (!bdi_write_congested(mapping->backing_dev_info))
120                         __filemap_fdatawrite_range(mapping, offset, endbyte,
121                                                    WB_SYNC_NONE);
122
123                 /* First and last FULL page! */
124                 start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
125                 end_index = (endbyte >> PAGE_CACHE_SHIFT);
126
127                 if (end_index >= start_index)
128                         invalidate_mapping_pages(mapping, start_index,
129                                                 end_index);
130                 break;
131         default:
132                 ret = -EINVAL;
133         }
134 out:
135         fput(file);
136         return ret;
137 }
138 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
139 asmlinkage long SyS_fadvise64_64(long fd, loff_t offset, loff_t len, long advice)
140 {
141         return SYSC_fadvise64_64((int) fd, offset, len, (int) advice);
142 }
143 SYSCALL_ALIAS(sys_fadvise64_64, SyS_fadvise64_64);
144 #endif
145
146 #ifdef __ARCH_WANT_SYS_FADVISE64
147
148 SYSCALL_DEFINE(fadvise64)(int fd, loff_t offset, size_t len, int advice)
149 {
150         return sys_fadvise64_64(fd, offset, len, advice);
151 }
152 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
153 asmlinkage long SyS_fadvise64(long fd, loff_t offset, long len, long advice)
154 {
155         return SYSC_fadvise64((int) fd, offset, (size_t)len, (int)advice);
156 }
157 SYSCALL_ALIAS(sys_fadvise64, SyS_fadvise64);
158 #endif
159
160 #endif