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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_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice) | |
29 | { | |
30 | struct fd f = fdget(fd); | |
31 | struct inode *inode; | |
32 | struct address_space *mapping; | |
33 | struct backing_dev_info *bdi; | |
34 | loff_t endbyte; /* inclusive */ | |
35 | pgoff_t start_index; | |
36 | pgoff_t end_index; | |
37 | unsigned long nrpages; | |
38 | int ret = 0; | |
39 | ||
40 | if (!f.file) | |
41 | return -EBADF; | |
42 | ||
43 | inode = file_inode(f.file); | |
44 | if (S_ISFIFO(inode->i_mode)) { | |
45 | ret = -ESPIPE; | |
46 | goto out; | |
47 | } | |
48 | ||
49 | mapping = f.file->f_mapping; | |
50 | if (!mapping || len < 0) { | |
51 | ret = -EINVAL; | |
52 | goto out; | |
53 | } | |
54 | ||
55 | if (IS_DAX(inode)) { | |
56 | switch (advice) { | |
57 | case POSIX_FADV_NORMAL: | |
58 | case POSIX_FADV_RANDOM: | |
59 | case POSIX_FADV_SEQUENTIAL: | |
60 | case POSIX_FADV_WILLNEED: | |
61 | case POSIX_FADV_NOREUSE: | |
62 | case POSIX_FADV_DONTNEED: | |
63 | /* no bad return value, but ignore advice */ | |
64 | break; | |
65 | default: | |
66 | ret = -EINVAL; | |
67 | } | |
68 | goto out; | |
69 | } | |
70 | ||
71 | /* Careful about overflows. Len == 0 means "as much as possible" */ | |
72 | endbyte = offset + len; | |
73 | if (!len || endbyte < len) | |
74 | endbyte = -1; | |
75 | else | |
76 | endbyte--; /* inclusive */ | |
77 | ||
78 | bdi = inode_to_bdi(mapping->host); | |
79 | ||
80 | switch (advice) { | |
81 | case POSIX_FADV_NORMAL: | |
82 | f.file->f_ra.ra_pages = bdi->ra_pages; | |
83 | spin_lock(&f.file->f_lock); | |
84 | f.file->f_mode &= ~FMODE_RANDOM; | |
85 | spin_unlock(&f.file->f_lock); | |
86 | break; | |
87 | case POSIX_FADV_RANDOM: | |
88 | spin_lock(&f.file->f_lock); | |
89 | f.file->f_mode |= FMODE_RANDOM; | |
90 | spin_unlock(&f.file->f_lock); | |
91 | break; | |
92 | case POSIX_FADV_SEQUENTIAL: | |
93 | f.file->f_ra.ra_pages = bdi->ra_pages * 2; | |
94 | spin_lock(&f.file->f_lock); | |
95 | f.file->f_mode &= ~FMODE_RANDOM; | |
96 | spin_unlock(&f.file->f_lock); | |
97 | break; | |
98 | case POSIX_FADV_WILLNEED: | |
99 | /* First and last PARTIAL page! */ | |
100 | start_index = offset >> PAGE_SHIFT; | |
101 | end_index = endbyte >> PAGE_SHIFT; | |
102 | ||
103 | /* Careful about overflow on the "+1" */ | |
104 | nrpages = end_index - start_index + 1; | |
105 | if (!nrpages) | |
106 | nrpages = ~0UL; | |
107 | ||
108 | /* | |
109 | * Ignore return value because fadvise() shall return | |
110 | * success even if filesystem can't retrieve a hint, | |
111 | */ | |
112 | force_page_cache_readahead(mapping, f.file, start_index, | |
113 | nrpages); | |
114 | break; | |
115 | case POSIX_FADV_NOREUSE: | |
116 | break; | |
117 | case POSIX_FADV_DONTNEED: | |
118 | if (!inode_write_congested(mapping->host)) | |
119 | __filemap_fdatawrite_range(mapping, offset, endbyte, | |
120 | WB_SYNC_NONE); | |
121 | ||
122 | /* | |
123 | * First and last FULL page! Partial pages are deliberately | |
124 | * preserved on the expectation that it is better to preserve | |
125 | * needed memory than to discard unneeded memory. | |
126 | */ | |
127 | start_index = (offset+(PAGE_SIZE-1)) >> PAGE_SHIFT; | |
128 | end_index = (endbyte >> PAGE_SHIFT); | |
129 | if ((endbyte & ~PAGE_MASK) != ~PAGE_MASK) { | |
130 | /* First page is tricky as 0 - 1 = -1, but pgoff_t | |
131 | * is unsigned, so the end_index >= start_index | |
132 | * check below would be true and we'll discard the whole | |
133 | * file cache which is not what was asked. | |
134 | */ | |
135 | if (end_index == 0) | |
136 | break; | |
137 | ||
138 | end_index--; | |
139 | } | |
140 | ||
141 | if (end_index >= start_index) { | |
142 | unsigned long count; | |
143 | ||
144 | /* | |
145 | * It's common to FADV_DONTNEED right after | |
146 | * the read or write that instantiates the | |
147 | * pages, in which case there will be some | |
148 | * sitting on the local LRU cache. Try to | |
149 | * avoid the expensive remote drain and the | |
150 | * second cache tree walk below by flushing | |
151 | * them out right away. | |
152 | */ | |
153 | lru_add_drain(); | |
154 | ||
155 | count = invalidate_mapping_pages(mapping, | |
156 | start_index, end_index); | |
157 | ||
158 | /* | |
159 | * If fewer pages were invalidated than expected then | |
160 | * it is possible that some of the pages were on | |
161 | * a per-cpu pagevec for a remote CPU. Drain all | |
162 | * pagevecs and try again. | |
163 | */ | |
164 | if (count < (end_index - start_index + 1)) { | |
165 | lru_add_drain_all(); | |
166 | invalidate_mapping_pages(mapping, start_index, | |
167 | end_index); | |
168 | } | |
169 | } | |
170 | break; | |
171 | default: | |
172 | ret = -EINVAL; | |
173 | } | |
174 | out: | |
175 | fdput(f); | |
176 | return ret; | |
177 | } | |
178 | ||
179 | #ifdef __ARCH_WANT_SYS_FADVISE64 | |
180 | ||
181 | SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice) | |
182 | { | |
183 | return sys_fadvise64_64(fd, offset, len, advice); | |
184 | } | |
185 | ||
186 | #endif |