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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/pagevec.h>
18#include <linux/fadvise.h>
19#include <linux/writeback.h>
20#include <linux/syscalls.h>
21#include <linux/swap.h>
22
23#include <asm/unistd.h>
24
25/*
26 * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
27 * deactivate the pages and clear PG_Referenced.
28 */
29
30int ksys_fadvise64_64(int fd, loff_t offset, loff_t len, int advice)
31{
32 struct fd f = fdget(fd);
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 int ret = 0;
41
42 if (!f.file)
43 return -EBADF;
44
45 inode = file_inode(f.file);
46 if (S_ISFIFO(inode->i_mode)) {
47 ret = -ESPIPE;
48 goto out;
49 }
50
51 mapping = f.file->f_mapping;
52 if (!mapping || len < 0) {
53 ret = -EINVAL;
54 goto out;
55 }
56
57 bdi = inode_to_bdi(mapping->host);
58
59 if (IS_DAX(inode) || (bdi == &noop_backing_dev_info)) {
60 switch (advice) {
61 case POSIX_FADV_NORMAL:
62 case POSIX_FADV_RANDOM:
63 case POSIX_FADV_SEQUENTIAL:
64 case POSIX_FADV_WILLNEED:
65 case POSIX_FADV_NOREUSE:
66 case POSIX_FADV_DONTNEED:
67 /* no bad return value, but ignore advice */
68 break;
69 default:
70 ret = -EINVAL;
71 }
72 goto out;
73 }
74
75 /* Careful about overflows. Len == 0 means "as much as possible" */
76 endbyte = offset + len;
77 if (!len || endbyte < len)
78 endbyte = -1;
79 else
80 endbyte--; /* inclusive */
81
82 switch (advice) {
83 case POSIX_FADV_NORMAL:
84 f.file->f_ra.ra_pages = bdi->ra_pages;
85 spin_lock(&f.file->f_lock);
86 f.file->f_mode &= ~FMODE_RANDOM;
87 spin_unlock(&f.file->f_lock);
88 break;
89 case POSIX_FADV_RANDOM:
90 spin_lock(&f.file->f_lock);
91 f.file->f_mode |= FMODE_RANDOM;
92 spin_unlock(&f.file->f_lock);
93 break;
94 case POSIX_FADV_SEQUENTIAL:
95 f.file->f_ra.ra_pages = bdi->ra_pages * 2;
96 spin_lock(&f.file->f_lock);
97 f.file->f_mode &= ~FMODE_RANDOM;
98 spin_unlock(&f.file->f_lock);
99 break;
100 case POSIX_FADV_WILLNEED:
101 /* First and last PARTIAL page! */
102 start_index = offset >> PAGE_SHIFT;
103 end_index = endbyte >> PAGE_SHIFT;
104
105 /* Careful about overflow on the "+1" */
106 nrpages = end_index - start_index + 1;
107 if (!nrpages)
108 nrpages = ~0UL;
109
110 /*
111 * Ignore return value because fadvise() shall return
112 * success even if filesystem can't retrieve a hint,
113 */
114 force_page_cache_readahead(mapping, f.file, start_index,
115 nrpages);
116 break;
117 case POSIX_FADV_NOREUSE:
118 break;
119 case POSIX_FADV_DONTNEED:
120 if (!inode_write_congested(mapping->host))
121 __filemap_fdatawrite_range(mapping, offset, endbyte,
122 WB_SYNC_NONE);
123
124 /*
125 * First and last FULL page! Partial pages are deliberately
126 * preserved on the expectation that it is better to preserve
127 * needed memory than to discard unneeded memory.
128 */
129 start_index = (offset+(PAGE_SIZE-1)) >> PAGE_SHIFT;
130 end_index = (endbyte >> PAGE_SHIFT);
131 /*
132 * The page at end_index will be inclusively discarded according
133 * by invalidate_mapping_pages(), so subtracting 1 from
134 * end_index means we will skip the last page. But if endbyte
135 * is page aligned or is at the end of file, we should not skip
136 * that page - discarding the last page is safe enough.
137 */
138 if ((endbyte & ~PAGE_MASK) != ~PAGE_MASK &&
139 endbyte != inode->i_size - 1) {
140 /* First page is tricky as 0 - 1 = -1, but pgoff_t
141 * is unsigned, so the end_index >= start_index
142 * check below would be true and we'll discard the whole
143 * file cache which is not what was asked.
144 */
145 if (end_index == 0)
146 break;
147
148 end_index--;
149 }
150
151 if (end_index >= start_index) {
152 unsigned long count;
153
154 /*
155 * It's common to FADV_DONTNEED right after
156 * the read or write that instantiates the
157 * pages, in which case there will be some
158 * sitting on the local LRU cache. Try to
159 * avoid the expensive remote drain and the
160 * second cache tree walk below by flushing
161 * them out right away.
162 */
163 lru_add_drain();
164
165 count = invalidate_mapping_pages(mapping,
166 start_index, end_index);
167
168 /*
169 * If fewer pages were invalidated than expected then
170 * it is possible that some of the pages were on
171 * a per-cpu pagevec for a remote CPU. Drain all
172 * pagevecs and try again.
173 */
174 if (count < (end_index - start_index + 1)) {
175 lru_add_drain_all();
176 invalidate_mapping_pages(mapping, start_index,
177 end_index);
178 }
179 }
180 break;
181 default:
182 ret = -EINVAL;
183 }
184out:
185 fdput(f);
186 return ret;
187}
188
189SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
190{
191 return ksys_fadvise64_64(fd, offset, len, advice);
192}
193
194#ifdef __ARCH_WANT_SYS_FADVISE64
195
196SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
197{
198 return ksys_fadvise64_64(fd, offset, len, advice);
199}
200
201#endif
1/*
2 * mm/fadvise.c
3 *
4 * Copyright (C) 2002, Linus Torvalds
5 *
6 * 11Jan2003 Andrew Morton
7 * Initial version.
8 */
9
10#include <linux/kernel.h>
11#include <linux/file.h>
12#include <linux/fs.h>
13#include <linux/mm.h>
14#include <linux/pagemap.h>
15#include <linux/backing-dev.h>
16#include <linux/pagevec.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/*
25 * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
26 * deactivate the pages and clear PG_Referenced.
27 */
28SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
29{
30 struct fd f = fdget(fd);
31 struct address_space *mapping;
32 struct backing_dev_info *bdi;
33 loff_t endbyte; /* inclusive */
34 pgoff_t start_index;
35 pgoff_t end_index;
36 unsigned long nrpages;
37 int ret = 0;
38
39 if (!f.file)
40 return -EBADF;
41
42 if (S_ISFIFO(file_inode(f.file)->i_mode)) {
43 ret = -ESPIPE;
44 goto out;
45 }
46
47 mapping = f.file->f_mapping;
48 if (!mapping || len < 0) {
49 ret = -EINVAL;
50 goto out;
51 }
52
53 if (mapping->a_ops->get_xip_mem) {
54 switch (advice) {
55 case POSIX_FADV_NORMAL:
56 case POSIX_FADV_RANDOM:
57 case POSIX_FADV_SEQUENTIAL:
58 case POSIX_FADV_WILLNEED:
59 case POSIX_FADV_NOREUSE:
60 case POSIX_FADV_DONTNEED:
61 /* no bad return value, but ignore advice */
62 break;
63 default:
64 ret = -EINVAL;
65 }
66 goto out;
67 }
68
69 /* Careful about overflows. Len == 0 means "as much as possible" */
70 endbyte = offset + len;
71 if (!len || endbyte < len)
72 endbyte = -1;
73 else
74 endbyte--; /* inclusive */
75
76 bdi = mapping->backing_dev_info;
77
78 switch (advice) {
79 case POSIX_FADV_NORMAL:
80 f.file->f_ra.ra_pages = bdi->ra_pages;
81 spin_lock(&f.file->f_lock);
82 f.file->f_mode &= ~FMODE_RANDOM;
83 spin_unlock(&f.file->f_lock);
84 break;
85 case POSIX_FADV_RANDOM:
86 spin_lock(&f.file->f_lock);
87 f.file->f_mode |= FMODE_RANDOM;
88 spin_unlock(&f.file->f_lock);
89 break;
90 case POSIX_FADV_SEQUENTIAL:
91 f.file->f_ra.ra_pages = bdi->ra_pages * 2;
92 spin_lock(&f.file->f_lock);
93 f.file->f_mode &= ~FMODE_RANDOM;
94 spin_unlock(&f.file->f_lock);
95 break;
96 case POSIX_FADV_WILLNEED:
97 /* First and last PARTIAL page! */
98 start_index = offset >> PAGE_CACHE_SHIFT;
99 end_index = endbyte >> PAGE_CACHE_SHIFT;
100
101 /* Careful about overflow on the "+1" */
102 nrpages = end_index - start_index + 1;
103 if (!nrpages)
104 nrpages = ~0UL;
105
106 /*
107 * Ignore return value because fadvise() shall return
108 * success even if filesystem can't retrieve a hint,
109 */
110 force_page_cache_readahead(mapping, f.file, start_index,
111 nrpages);
112 break;
113 case POSIX_FADV_NOREUSE:
114 break;
115 case POSIX_FADV_DONTNEED:
116 if (!bdi_write_congested(mapping->backing_dev_info))
117 __filemap_fdatawrite_range(mapping, offset, endbyte,
118 WB_SYNC_NONE);
119
120 /* First and last FULL page! */
121 start_index = (offset+(PAGE_CACHE_SIZE-1)) >> PAGE_CACHE_SHIFT;
122 end_index = (endbyte >> PAGE_CACHE_SHIFT);
123
124 if (end_index >= start_index) {
125 unsigned long count = invalidate_mapping_pages(mapping,
126 start_index, end_index);
127
128 /*
129 * If fewer pages were invalidated than expected then
130 * it is possible that some of the pages were on
131 * a per-cpu pagevec for a remote CPU. Drain all
132 * pagevecs and try again.
133 */
134 if (count < (end_index - start_index + 1)) {
135 lru_add_drain_all();
136 invalidate_mapping_pages(mapping, start_index,
137 end_index);
138 }
139 }
140 break;
141 default:
142 ret = -EINVAL;
143 }
144out:
145 fdput(f);
146 return ret;
147}
148
149#ifdef __ARCH_WANT_SYS_FADVISE64
150
151SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
152{
153 return sys_fadvise64_64(fd, offset, len, advice);
154}
155
156#endif