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1 | // SPDX-License-Identifier: GPL-2.0 | |
2 | /* | |
3 | * mm/fadvise.c | |
4 | * | |
5 | * Copyright (C) 2002, Linus Torvalds | |
6 | * | |
7 | * 11Jan2003 Andrew Morton | |
8 | * Initial version. | |
9 | */ | |
10 | ||
11 | #include <linux/kernel.h> | |
12 | #include <linux/file.h> | |
13 | #include <linux/fs.h> | |
14 | #include <linux/mm.h> | |
15 | #include <linux/pagemap.h> | |
16 | #include <linux/backing-dev.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 | #include "internal.h" | |
25 | ||
26 | /* | |
27 | * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could | |
28 | * deactivate the pages and clear PG_Referenced. | |
29 | */ | |
30 | ||
31 | int generic_fadvise(struct file *file, loff_t offset, loff_t len, int advice) | |
32 | { | |
33 | struct inode *inode; | |
34 | struct address_space *mapping; | |
35 | struct backing_dev_info *bdi; | |
36 | loff_t endbyte; /* inclusive */ | |
37 | pgoff_t start_index; | |
38 | pgoff_t end_index; | |
39 | unsigned long nrpages; | |
40 | ||
41 | inode = file_inode(file); | |
42 | if (S_ISFIFO(inode->i_mode)) | |
43 | return -ESPIPE; | |
44 | ||
45 | mapping = file->f_mapping; | |
46 | if (!mapping || len < 0) | |
47 | return -EINVAL; | |
48 | ||
49 | bdi = inode_to_bdi(mapping->host); | |
50 | ||
51 | if (IS_DAX(inode) || (bdi == &noop_backing_dev_info)) { | |
52 | switch (advice) { | |
53 | case POSIX_FADV_NORMAL: | |
54 | case POSIX_FADV_RANDOM: | |
55 | case POSIX_FADV_SEQUENTIAL: | |
56 | case POSIX_FADV_WILLNEED: | |
57 | case POSIX_FADV_NOREUSE: | |
58 | case POSIX_FADV_DONTNEED: | |
59 | /* no bad return value, but ignore advice */ | |
60 | break; | |
61 | default: | |
62 | return -EINVAL; | |
63 | } | |
64 | return 0; | |
65 | } | |
66 | ||
67 | /* | |
68 | * Careful about overflows. Len == 0 means "as much as possible". Use | |
69 | * unsigned math because signed overflows are undefined and UBSan | |
70 | * complains. | |
71 | */ | |
72 | endbyte = (u64)offset + (u64)len; | |
73 | if (!len || endbyte < len) | |
74 | endbyte = LLONG_MAX; | |
75 | else | |
76 | endbyte--; /* inclusive */ | |
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 | FMODE_NOREUSE); | |
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 | /* First and last PARTIAL page! */ | |
98 | start_index = offset >> PAGE_SHIFT; | |
99 | end_index = endbyte >> PAGE_SHIFT; | |
100 | ||
101 | /* Careful about overflow on the "+1" */ | |
102 | nrpages = end_index - start_index + 1; | |
103 | if (!nrpages) | |
104 | nrpages = ~0UL; | |
105 | ||
106 | force_page_cache_readahead(mapping, file, start_index, nrpages); | |
107 | break; | |
108 | case POSIX_FADV_NOREUSE: | |
109 | spin_lock(&file->f_lock); | |
110 | file->f_mode |= FMODE_NOREUSE; | |
111 | spin_unlock(&file->f_lock); | |
112 | break; | |
113 | case POSIX_FADV_DONTNEED: | |
114 | __filemap_fdatawrite_range(mapping, offset, endbyte, | |
115 | WB_SYNC_NONE); | |
116 | ||
117 | /* | |
118 | * First and last FULL page! Partial pages are deliberately | |
119 | * preserved on the expectation that it is better to preserve | |
120 | * needed memory than to discard unneeded memory. | |
121 | */ | |
122 | start_index = (offset+(PAGE_SIZE-1)) >> PAGE_SHIFT; | |
123 | end_index = (endbyte >> PAGE_SHIFT); | |
124 | /* | |
125 | * The page at end_index will be inclusively discarded according | |
126 | * by invalidate_mapping_pages(), so subtracting 1 from | |
127 | * end_index means we will skip the last page. But if endbyte | |
128 | * is page aligned or is at the end of file, we should not skip | |
129 | * that page - discarding the last page is safe enough. | |
130 | */ | |
131 | if ((endbyte & ~PAGE_MASK) != ~PAGE_MASK && | |
132 | endbyte != inode->i_size - 1) { | |
133 | /* First page is tricky as 0 - 1 = -1, but pgoff_t | |
134 | * is unsigned, so the end_index >= start_index | |
135 | * check below would be true and we'll discard the whole | |
136 | * file cache which is not what was asked. | |
137 | */ | |
138 | if (end_index == 0) | |
139 | break; | |
140 | ||
141 | end_index--; | |
142 | } | |
143 | ||
144 | if (end_index >= start_index) { | |
145 | unsigned long nr_failed = 0; | |
146 | ||
147 | /* | |
148 | * It's common to FADV_DONTNEED right after | |
149 | * the read or write that instantiates the | |
150 | * pages, in which case there will be some | |
151 | * sitting on the local LRU cache. Try to | |
152 | * avoid the expensive remote drain and the | |
153 | * second cache tree walk below by flushing | |
154 | * them out right away. | |
155 | */ | |
156 | lru_add_drain(); | |
157 | ||
158 | mapping_try_invalidate(mapping, start_index, end_index, | |
159 | &nr_failed); | |
160 | ||
161 | /* | |
162 | * The failures may be due to the folio being | |
163 | * in the LRU cache of a remote CPU. Drain all | |
164 | * caches and try again. | |
165 | */ | |
166 | if (nr_failed) { | |
167 | lru_add_drain_all(); | |
168 | invalidate_mapping_pages(mapping, start_index, | |
169 | end_index); | |
170 | } | |
171 | } | |
172 | break; | |
173 | default: | |
174 | return -EINVAL; | |
175 | } | |
176 | return 0; | |
177 | } | |
178 | EXPORT_SYMBOL(generic_fadvise); | |
179 | ||
180 | int vfs_fadvise(struct file *file, loff_t offset, loff_t len, int advice) | |
181 | { | |
182 | if (file->f_op->fadvise) | |
183 | return file->f_op->fadvise(file, offset, len, advice); | |
184 | ||
185 | return generic_fadvise(file, offset, len, advice); | |
186 | } | |
187 | EXPORT_SYMBOL(vfs_fadvise); | |
188 | ||
189 | #ifdef CONFIG_ADVISE_SYSCALLS | |
190 | ||
191 | int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice) | |
192 | { | |
193 | struct fd f = fdget(fd); | |
194 | int ret; | |
195 | ||
196 | if (!f.file) | |
197 | return -EBADF; | |
198 | ||
199 | ret = vfs_fadvise(f.file, offset, len, advice); | |
200 | ||
201 | fdput(f); | |
202 | return ret; | |
203 | } | |
204 | ||
205 | SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice) | |
206 | { | |
207 | return ksys_fadvise64_64(fd, offset, len, advice); | |
208 | } | |
209 | ||
210 | #ifdef __ARCH_WANT_SYS_FADVISE64 | |
211 | ||
212 | SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice) | |
213 | { | |
214 | return ksys_fadvise64_64(fd, offset, len, advice); | |
215 | } | |
216 | ||
217 | #endif | |
218 | ||
219 | #if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FADVISE64_64) | |
220 | ||
221 | COMPAT_SYSCALL_DEFINE6(fadvise64_64, int, fd, compat_arg_u64_dual(offset), | |
222 | compat_arg_u64_dual(len), int, advice) | |
223 | { | |
224 | return ksys_fadvise64_64(fd, compat_arg_u64_glue(offset), | |
225 | compat_arg_u64_glue(len), advice); | |
226 | } | |
227 | ||
228 | #endif | |
229 | #endif |