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1 // SPDX-License-Identifier: GPL-2.0
5 * Copyright (C) 2002, Linus Torvalds
7 * 11Jan2003 Andrew Morton
11 #include <linux/kernel.h>
12 #include <linux/file.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>
23 #include <asm/unistd.h>
26 * POSIX_FADV_WILLNEED could set PG_Referenced, and POSIX_FADV_NOREUSE could
27 * deactivate the pages and clear PG_Referenced.
30 int ksys_fadvise64_64(int fd
, loff_t offset
, loff_t len
, int advice
)
32 struct fd f
= fdget(fd
);
34 struct address_space
*mapping
;
35 struct backing_dev_info
*bdi
;
36 loff_t endbyte
; /* inclusive */
39 unsigned long nrpages
;
45 inode
= file_inode(f
.file
);
46 if (S_ISFIFO(inode
->i_mode
)) {
51 mapping
= f
.file
->f_mapping
;
52 if (!mapping
|| len
< 0) {
57 bdi
= inode_to_bdi(mapping
->host
);
59 if (IS_DAX(inode
) || (bdi
== &noop_backing_dev_info
)) {
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 */
76 * Careful about overflows. Len == 0 means "as much as possible". Use
77 * unsigned math because signed overflows are undefined and UBSan
80 endbyte
= (u64
)offset
+ (u64
)len
;
81 if (!len
|| endbyte
< len
)
84 endbyte
--; /* inclusive */
87 case POSIX_FADV_NORMAL
:
88 f
.file
->f_ra
.ra_pages
= bdi
->ra_pages
;
89 spin_lock(&f
.file
->f_lock
);
90 f
.file
->f_mode
&= ~FMODE_RANDOM
;
91 spin_unlock(&f
.file
->f_lock
);
93 case POSIX_FADV_RANDOM
:
94 spin_lock(&f
.file
->f_lock
);
95 f
.file
->f_mode
|= FMODE_RANDOM
;
96 spin_unlock(&f
.file
->f_lock
);
98 case POSIX_FADV_SEQUENTIAL
:
99 f
.file
->f_ra
.ra_pages
= bdi
->ra_pages
* 2;
100 spin_lock(&f
.file
->f_lock
);
101 f
.file
->f_mode
&= ~FMODE_RANDOM
;
102 spin_unlock(&f
.file
->f_lock
);
104 case POSIX_FADV_WILLNEED
:
105 /* First and last PARTIAL page! */
106 start_index
= offset
>> PAGE_SHIFT
;
107 end_index
= endbyte
>> PAGE_SHIFT
;
109 /* Careful about overflow on the "+1" */
110 nrpages
= end_index
- start_index
+ 1;
115 * Ignore return value because fadvise() shall return
116 * success even if filesystem can't retrieve a hint,
118 force_page_cache_readahead(mapping
, f
.file
, start_index
,
121 case POSIX_FADV_NOREUSE
:
123 case POSIX_FADV_DONTNEED
:
124 if (!inode_write_congested(mapping
->host
))
125 __filemap_fdatawrite_range(mapping
, offset
, endbyte
,
129 * First and last FULL page! Partial pages are deliberately
130 * preserved on the expectation that it is better to preserve
131 * needed memory than to discard unneeded memory.
133 start_index
= (offset
+(PAGE_SIZE
-1)) >> PAGE_SHIFT
;
134 end_index
= (endbyte
>> PAGE_SHIFT
);
136 * The page at end_index will be inclusively discarded according
137 * by invalidate_mapping_pages(), so subtracting 1 from
138 * end_index means we will skip the last page. But if endbyte
139 * is page aligned or is at the end of file, we should not skip
140 * that page - discarding the last page is safe enough.
142 if ((endbyte
& ~PAGE_MASK
) != ~PAGE_MASK
&&
143 endbyte
!= inode
->i_size
- 1) {
144 /* First page is tricky as 0 - 1 = -1, but pgoff_t
145 * is unsigned, so the end_index >= start_index
146 * check below would be true and we'll discard the whole
147 * file cache which is not what was asked.
155 if (end_index
>= start_index
) {
159 * It's common to FADV_DONTNEED right after
160 * the read or write that instantiates the
161 * pages, in which case there will be some
162 * sitting on the local LRU cache. Try to
163 * avoid the expensive remote drain and the
164 * second cache tree walk below by flushing
165 * them out right away.
169 count
= invalidate_mapping_pages(mapping
,
170 start_index
, end_index
);
173 * If fewer pages were invalidated than expected then
174 * it is possible that some of the pages were on
175 * a per-cpu pagevec for a remote CPU. Drain all
176 * pagevecs and try again.
178 if (count
< (end_index
- start_index
+ 1)) {
180 invalidate_mapping_pages(mapping
, start_index
,
193 SYSCALL_DEFINE4(fadvise64_64
, int, fd
, loff_t
, offset
, loff_t
, len
, int, advice
)
195 return ksys_fadvise64_64(fd
, offset
, len
, advice
);
198 #ifdef __ARCH_WANT_SYS_FADVISE64
200 SYSCALL_DEFINE4(fadvise64
, int, fd
, loff_t
, offset
, size_t, len
, int, advice
)
202 return ksys_fadvise64_64(fd
, offset
, len
, advice
);