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(f: 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(inode: 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(lock: &file->f_lock); |
82 | file->f_mode &= ~(FMODE_RANDOM | FMODE_NOREUSE); |
83 | spin_unlock(lock: &file->f_lock); |
84 | break; |
85 | case POSIX_FADV_RANDOM: |
86 | spin_lock(lock: &file->f_lock); |
87 | file->f_mode |= FMODE_RANDOM; |
88 | spin_unlock(lock: &file->f_lock); |
89 | break; |
90 | case POSIX_FADV_SEQUENTIAL: |
91 | file->f_ra.ra_pages = bdi->ra_pages * 2; |
92 | spin_lock(lock: &file->f_lock); |
93 | file->f_mode &= ~FMODE_RANDOM; |
94 | spin_unlock(lock: &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, index: start_index, nr_to_read: nrpages); |
107 | break; |
108 | case POSIX_FADV_NOREUSE: |
109 | spin_lock(lock: &file->f_lock); |
110 | file->f_mode |= FMODE_NOREUSE; |
111 | spin_unlock(lock: &file->f_lock); |
112 | break; |
113 | case POSIX_FADV_DONTNEED: |
114 | __filemap_fdatawrite_range(mapping, start: offset, end: endbyte, |
115 | sync_mode: 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: start_index, end: end_index, |
159 | nr_failed: &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: start_index, |
169 | end: 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(fd: 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 |
230 | |