Line data Source code
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 0 : 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 0 : inode = file_inode(file);
42 0 : if (S_ISFIFO(inode->i_mode))
43 : return -ESPIPE;
44 :
45 0 : mapping = file->f_mapping;
46 0 : if (!mapping || len < 0)
47 : return -EINVAL;
48 :
49 0 : bdi = inode_to_bdi(mapping->host);
50 :
51 0 : if (IS_DAX(inode) || (bdi == &noop_backing_dev_info)) {
52 0 : 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 0 : 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 0 : endbyte = (u64)offset + (u64)len;
73 0 : if (!len || endbyte < len)
74 : endbyte = LLONG_MAX;
75 : else
76 0 : endbyte--; /* inclusive */
77 :
78 0 : switch (advice) {
79 : case POSIX_FADV_NORMAL:
80 0 : file->f_ra.ra_pages = bdi->ra_pages;
81 0 : spin_lock(&file->f_lock);
82 0 : file->f_mode &= ~(FMODE_RANDOM | FMODE_NOREUSE);
83 0 : spin_unlock(&file->f_lock);
84 : break;
85 : case POSIX_FADV_RANDOM:
86 0 : spin_lock(&file->f_lock);
87 0 : file->f_mode |= FMODE_RANDOM;
88 0 : spin_unlock(&file->f_lock);
89 : break;
90 : case POSIX_FADV_SEQUENTIAL:
91 0 : file->f_ra.ra_pages = bdi->ra_pages * 2;
92 0 : spin_lock(&file->f_lock);
93 0 : file->f_mode &= ~FMODE_RANDOM;
94 0 : spin_unlock(&file->f_lock);
95 : break;
96 : case POSIX_FADV_WILLNEED:
97 : /* First and last PARTIAL page! */
98 0 : start_index = offset >> PAGE_SHIFT;
99 0 : end_index = endbyte >> PAGE_SHIFT;
100 :
101 : /* Careful about overflow on the "+1" */
102 0 : nrpages = end_index - start_index + 1;
103 0 : if (!nrpages)
104 0 : nrpages = ~0UL;
105 :
106 : force_page_cache_readahead(mapping, file, start_index, nrpages);
107 : break;
108 : case POSIX_FADV_NOREUSE:
109 0 : spin_lock(&file->f_lock);
110 0 : file->f_mode |= FMODE_NOREUSE;
111 0 : spin_unlock(&file->f_lock);
112 : break;
113 : case POSIX_FADV_DONTNEED:
114 0 : __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 0 : start_index = (offset+(PAGE_SIZE-1)) >> PAGE_SHIFT;
123 0 : 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 0 : if ((endbyte & ~PAGE_MASK) != ~PAGE_MASK &&
132 0 : 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 0 : if (end_index == 0)
139 : break;
140 :
141 0 : end_index--;
142 : }
143 :
144 0 : if (end_index >= start_index) {
145 0 : 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 0 : lru_add_drain();
157 :
158 0 : 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 0 : if (nr_failed) {
167 0 : lru_add_drain_all();
168 0 : 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 0 : int vfs_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
181 : {
182 0 : if (file->f_op->fadvise)
183 0 : return file->f_op->fadvise(file, offset, len, advice);
184 :
185 0 : return generic_fadvise(file, offset, len, advice);
186 : }
187 : EXPORT_SYMBOL(vfs_fadvise);
188 :
189 : #ifdef CONFIG_ADVISE_SYSCALLS
190 :
191 0 : int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
192 : {
193 0 : struct fd f = fdget(fd);
194 : int ret;
195 :
196 0 : if (!f.file)
197 : return -EBADF;
198 :
199 0 : ret = vfs_fadvise(f.file, offset, len, advice);
200 :
201 0 : fdput(f);
202 : return ret;
203 : }
204 :
205 0 : SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
206 : {
207 0 : return ksys_fadvise64_64(fd, offset, len, advice);
208 : }
209 :
210 : #ifdef __ARCH_WANT_SYS_FADVISE64
211 :
212 0 : SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
213 : {
214 0 : 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
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