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
230
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