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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
31int 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 || offset < 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_flush_range(mapping, offset, endbyte);
115
116 /*
117 * First and last FULL page! Partial pages are deliberately
118 * preserved on the expectation that it is better to preserve
119 * needed memory than to discard unneeded memory.
120 */
121 start_index = (offset+(PAGE_SIZE-1)) >> PAGE_SHIFT;
122 end_index = (endbyte >> PAGE_SHIFT);
123 /*
124 * The page at end_index will be inclusively discarded according
125 * by invalidate_mapping_pages(), so subtracting 1 from
126 * end_index means we will skip the last page. But if endbyte
127 * is page aligned or is at the end of file, we should not skip
128 * that page - discarding the last page is safe enough.
129 */
130 if ((endbyte & ~PAGE_MASK) != ~PAGE_MASK &&
131 endbyte != inode->i_size - 1) {
132 /* First page is tricky as 0 - 1 = -1, but pgoff_t
133 * is unsigned, so the end_index >= start_index
134 * check below would be true and we'll discard the whole
135 * file cache which is not what was asked.
136 */
137 if (end_index == 0)
138 break;
139
140 end_index--;
141 }
142
143 if (end_index >= start_index) {
144 unsigned long nr_failed = 0;
145
146 /*
147 * It's common to FADV_DONTNEED right after
148 * the read or write that instantiates the
149 * pages, in which case there will be some
150 * sitting on the local LRU cache. Try to
151 * avoid the expensive remote drain and the
152 * second cache tree walk below by flushing
153 * them out right away.
154 */
155 lru_add_drain();
156
157 mapping_try_invalidate(mapping, start_index, end_index,
158 &nr_failed);
159
160 /*
161 * The failures may be due to the folio being
162 * in the LRU cache of a remote CPU. Drain all
163 * caches and try again.
164 */
165 if (nr_failed) {
166 lru_add_drain_all();
167 invalidate_mapping_pages(mapping, start_index,
168 end_index);
169 }
170 }
171 break;
172 default:
173 return -EINVAL;
174 }
175 return 0;
176}
177EXPORT_SYMBOL(generic_fadvise);
178
179int vfs_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
180{
181 if (file->f_op->fadvise)
182 return file->f_op->fadvise(file, offset, len, advice);
183
184 return generic_fadvise(file, offset, len, advice);
185}
186EXPORT_SYMBOL(vfs_fadvise);
187
188#ifdef CONFIG_ADVISE_SYSCALLS
189
190int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
191{
192 CLASS(fd, f)(fd);
193
194 if (fd_empty(f))
195 return -EBADF;
196
197 return vfs_fadvise(fd_file(f), offset, len, advice);
198}
199
200SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
201{
202 return ksys_fadvise64_64(fd, offset, len, advice);
203}
204
205#ifdef __ARCH_WANT_SYS_FADVISE64
206
207SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
208{
209 return ksys_fadvise64_64(fd, offset, len, advice);
210}
211
212#endif
213
214#if defined(CONFIG_COMPAT) && defined(__ARCH_WANT_COMPAT_FADVISE64_64)
215
216COMPAT_SYSCALL_DEFINE6(fadvise64_64, int, fd, compat_arg_u64_dual(offset),
217 compat_arg_u64_dual(len), int, advice)
218{
219 return ksys_fadvise64_64(fd, compat_arg_u64_glue(offset),
220 compat_arg_u64_glue(len), advice);
221}
222
223#endif
224#endif