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 */
SYSCALL_DEFINE4(fadvise64_64,int,fd,loff_t,offset,loff_t,len,int,advice)28 SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
29 {
30 struct fd f = fdget(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 (!f.file)
40 return -EBADF;
41
42 if (S_ISFIFO(file_inode(f.file)->i_mode)) {
43 ret = -ESPIPE;
44 goto out;
45 }
46
47 mapping = f.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 f.file->f_ra.ra_pages = bdi->ra_pages;
81 spin_lock(&f.file->f_lock);
82 f.file->f_mode &= ~FMODE_RANDOM;
83 spin_unlock(&f.file->f_lock);
84 break;
85 case POSIX_FADV_RANDOM:
86 spin_lock(&f.file->f_lock);
87 f.file->f_mode |= FMODE_RANDOM;
88 spin_unlock(&f.file->f_lock);
89 break;
90 case POSIX_FADV_SEQUENTIAL:
91 f.file->f_ra.ra_pages = bdi->ra_pages * 2;
92 spin_lock(&f.file->f_lock);
93 f.file->f_mode &= ~FMODE_RANDOM;
94 spin_unlock(&f.file->f_lock);
95 break;
96 case POSIX_FADV_WILLNEED:
97 /* First and last PARTIAL page! */
98 start_index = offset >> PAGE_CACHE_SHIFT;
99 end_index = endbyte >> PAGE_CACHE_SHIFT;
100
101 /* Careful about overflow on the "+1" */
102 nrpages = end_index - start_index + 1;
103 if (!nrpages)
104 nrpages = ~0UL;
105
106 /*
107 * Ignore return value because fadvise() shall return
108 * success even if filesystem can't retrieve a hint,
109 */
110 force_page_cache_readahead(mapping, f.file, start_index,
111 nrpages);
112 break;
113 case POSIX_FADV_NOREUSE:
114 break;
115 case POSIX_FADV_DONTNEED:
116 if (!bdi_write_congested(mapping->backing_dev_info))
117 __filemap_fdatawrite_range(mapping, offset, endbyte,
118 WB_SYNC_NONE);
119
120 /* First and last FULL page! */
121 start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
122 end_index = (endbyte >> PAGE_CACHE_SHIFT);
123
124 if (end_index >= start_index) {
125 unsigned long count = invalidate_mapping_pages(mapping,
126 start_index, end_index);
127
128 /*
129 * If fewer pages were invalidated than expected then
130 * it is possible that some of the pages were on
131 * a per-cpu pagevec for a remote CPU. Drain all
132 * pagevecs and try again.
133 */
134 if (count < (end_index - start_index + 1)) {
135 lru_add_drain_all();
136 invalidate_mapping_pages(mapping, start_index,
137 end_index);
138 }
139 }
140 break;
141 default:
142 ret = -EINVAL;
143 }
144 out:
145 fdput(f);
146 return ret;
147 }
148
149 #ifdef __ARCH_WANT_SYS_FADVISE64
150
SYSCALL_DEFINE4(fadvise64,int,fd,loff_t,offset,size_t,len,int,advice)151 SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
152 {
153 return sys_fadvise64_64(fd, offset, len, advice);
154 }
155
156 #endif
157