ALSA: pcm: potential uninitialized return values
[pandora-kernel.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 #include <linux/swap.h>
21
22 #include <asm/unistd.h>
23
24 /*
25  * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
26  * deactivate the pages and clear PG_Referenced.
27  */
28 SYSCALL_DEFINE(fadvise64_64)(int fd, loff_t offset, loff_t len, int advice)
29 {
30         struct file *file = fget(fd);
31         struct address_space *mapping;
32         struct backing_dev_info *bdi;
33         loff_t endbyte;                 /* inclusive */
34         pgoff_t start_index;
35         pgoff_t end_index;
36         unsigned long nrpages;
37         int ret = 0;
38
39         if (!file)
40                 return -EBADF;
41
42         if (S_ISFIFO(file->f_path.dentry->d_inode->i_mode)) {
43                 ret = -ESPIPE;
44                 goto out;
45         }
46
47         mapping = file->f_mapping;
48         if (!mapping || len < 0) {
49                 ret = -EINVAL;
50                 goto out;
51         }
52
53         if (mapping->a_ops->get_xip_mem) {
54                 switch (advice) {
55                 case POSIX_FADV_NORMAL:
56                 case POSIX_FADV_RANDOM:
57                 case POSIX_FADV_SEQUENTIAL:
58                 case POSIX_FADV_WILLNEED:
59                 case POSIX_FADV_NOREUSE:
60                 case POSIX_FADV_DONTNEED:
61                         /* no bad return value, but ignore advice */
62                         break;
63                 default:
64                         ret = -EINVAL;
65                 }
66                 goto out;
67         }
68
69         /* Careful about overflows. Len == 0 means "as much as possible" */
70         endbyte = offset + len;
71         if (!len || endbyte < len)
72                 endbyte = -1;
73         else
74                 endbyte--;              /* inclusive */
75
76         bdi = mapping->backing_dev_info;
77
78         switch (advice) {
79         case POSIX_FADV_NORMAL:
80                 file->f_ra.ra_pages = bdi->ra_pages;
81                 spin_lock(&file->f_lock);
82                 file->f_mode &= ~FMODE_RANDOM;
83                 spin_unlock(&file->f_lock);
84                 break;
85         case POSIX_FADV_RANDOM:
86                 spin_lock(&file->f_lock);
87                 file->f_mode |= FMODE_RANDOM;
88                 spin_unlock(&file->f_lock);
89                 break;
90         case POSIX_FADV_SEQUENTIAL:
91                 file->f_ra.ra_pages = bdi->ra_pages * 2;
92                 spin_lock(&file->f_lock);
93                 file->f_mode &= ~FMODE_RANDOM;
94                 spin_unlock(&file->f_lock);
95                 break;
96         case POSIX_FADV_WILLNEED:
97                 if (!mapping->a_ops->readpage) {
98                         ret = -EINVAL;
99                         break;
100                 }
101
102                 /* First and last PARTIAL page! */
103                 start_index = offset >> PAGE_CACHE_SHIFT;
104                 end_index = endbyte >> PAGE_CACHE_SHIFT;
105
106                 /* Careful about overflow on the "+1" */
107                 nrpages = end_index - start_index + 1;
108                 if (!nrpages)
109                         nrpages = ~0UL;
110                 
111                 ret = force_page_cache_readahead(mapping, file,
112                                 start_index,
113                                 nrpages);
114                 if (ret > 0)
115                         ret = 0;
116                 break;
117         case POSIX_FADV_NOREUSE:
118                 break;
119         case POSIX_FADV_DONTNEED:
120                 if (!bdi_write_congested(mapping->backing_dev_info))
121                         filemap_flush(mapping);
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                         unsigned long count = invalidate_mapping_pages(mapping,
129                                                 start_index, end_index);
130
131                         /*
132                          * If fewer pages were invalidated than expected then
133                          * it is possible that some of the pages were on
134                          * a per-cpu pagevec for a remote CPU. Drain all
135                          * pagevecs and try again.
136                          */
137                         if (count < (end_index - start_index + 1)) {
138                                 lru_add_drain_all();
139                                 invalidate_mapping_pages(mapping, start_index,
140                                                 end_index);
141                         }
142                 }
143                 break;
144         default:
145                 ret = -EINVAL;
146         }
147 out:
148         fput(file);
149         return ret;
150 }
151 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
152 asmlinkage long SyS_fadvise64_64(long fd, loff_t offset, loff_t len, long advice)
153 {
154         return SYSC_fadvise64_64((int) fd, offset, len, (int) advice);
155 }
156 SYSCALL_ALIAS(sys_fadvise64_64, SyS_fadvise64_64);
157 #endif
158
159 #ifdef __ARCH_WANT_SYS_FADVISE64
160
161 SYSCALL_DEFINE(fadvise64)(int fd, loff_t offset, size_t len, int advice)
162 {
163         return sys_fadvise64_64(fd, offset, len, advice);
164 }
165 #ifdef CONFIG_HAVE_SYSCALL_WRAPPERS
166 asmlinkage long SyS_fadvise64(long fd, loff_t offset, long len, long advice)
167 {
168         return SYSC_fadvise64((int) fd, offset, (size_t)len, (int)advice);
169 }
170 SYSCALL_ALIAS(sys_fadvise64, SyS_fadvise64);
171 #endif
172
173 #endif