]> git.proxmox.com Git - mirror_ubuntu-bionic-kernel.git/blob - mm/fadvise.c
Merge tag 'for-4.15-rc7-tag' of git://git.kernel.org/pub/scm/linux/kernel/git/kdave...
[mirror_ubuntu-bionic-kernel.git] / mm / fadvise.c
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 SYSCALL_DEFINE4(fadvise64_64, int, fd, loff_t, offset, loff_t, len, int, advice)
30 {
31 struct fd f = fdget(fd);
32 struct inode *inode;
33 struct address_space *mapping;
34 struct backing_dev_info *bdi;
35 loff_t endbyte; /* inclusive */
36 pgoff_t start_index;
37 pgoff_t end_index;
38 unsigned long nrpages;
39 int ret = 0;
40
41 if (!f.file)
42 return -EBADF;
43
44 inode = file_inode(f.file);
45 if (S_ISFIFO(inode->i_mode)) {
46 ret = -ESPIPE;
47 goto out;
48 }
49
50 mapping = f.file->f_mapping;
51 if (!mapping || len < 0) {
52 ret = -EINVAL;
53 goto out;
54 }
55
56 bdi = inode_to_bdi(mapping->host);
57
58 if (IS_DAX(inode) || (bdi == &noop_backing_dev_info)) {
59 switch (advice) {
60 case POSIX_FADV_NORMAL:
61 case POSIX_FADV_RANDOM:
62 case POSIX_FADV_SEQUENTIAL:
63 case POSIX_FADV_WILLNEED:
64 case POSIX_FADV_NOREUSE:
65 case POSIX_FADV_DONTNEED:
66 /* no bad return value, but ignore advice */
67 break;
68 default:
69 ret = -EINVAL;
70 }
71 goto out;
72 }
73
74 /* Careful about overflows. Len == 0 means "as much as possible" */
75 endbyte = offset + len;
76 if (!len || endbyte < len)
77 endbyte = -1;
78 else
79 endbyte--; /* inclusive */
80
81 switch (advice) {
82 case POSIX_FADV_NORMAL:
83 f.file->f_ra.ra_pages = bdi->ra_pages;
84 spin_lock(&f.file->f_lock);
85 f.file->f_mode &= ~FMODE_RANDOM;
86 spin_unlock(&f.file->f_lock);
87 break;
88 case POSIX_FADV_RANDOM:
89 spin_lock(&f.file->f_lock);
90 f.file->f_mode |= FMODE_RANDOM;
91 spin_unlock(&f.file->f_lock);
92 break;
93 case POSIX_FADV_SEQUENTIAL:
94 f.file->f_ra.ra_pages = bdi->ra_pages * 2;
95 spin_lock(&f.file->f_lock);
96 f.file->f_mode &= ~FMODE_RANDOM;
97 spin_unlock(&f.file->f_lock);
98 break;
99 case POSIX_FADV_WILLNEED:
100 /* First and last PARTIAL page! */
101 start_index = offset >> PAGE_SHIFT;
102 end_index = endbyte >> PAGE_SHIFT;
103
104 /* Careful about overflow on the "+1" */
105 nrpages = end_index - start_index + 1;
106 if (!nrpages)
107 nrpages = ~0UL;
108
109 /*
110 * Ignore return value because fadvise() shall return
111 * success even if filesystem can't retrieve a hint,
112 */
113 force_page_cache_readahead(mapping, f.file, start_index,
114 nrpages);
115 break;
116 case POSIX_FADV_NOREUSE:
117 break;
118 case POSIX_FADV_DONTNEED:
119 if (!inode_write_congested(mapping->host))
120 __filemap_fdatawrite_range(mapping, offset, endbyte,
121 WB_SYNC_NONE);
122
123 /*
124 * First and last FULL page! Partial pages are deliberately
125 * preserved on the expectation that it is better to preserve
126 * needed memory than to discard unneeded memory.
127 */
128 start_index = (offset+(PAGE_SIZE-1)) >> PAGE_SHIFT;
129 end_index = (endbyte >> PAGE_SHIFT);
130 if ((endbyte & ~PAGE_MASK) != ~PAGE_MASK) {
131 /* First page is tricky as 0 - 1 = -1, but pgoff_t
132 * is unsigned, so the end_index >= start_index
133 * check below would be true and we'll discard the whole
134 * file cache which is not what was asked.
135 */
136 if (end_index == 0)
137 break;
138
139 end_index--;
140 }
141
142 if (end_index >= start_index) {
143 unsigned long count;
144
145 /*
146 * It's common to FADV_DONTNEED right after
147 * the read or write that instantiates the
148 * pages, in which case there will be some
149 * sitting on the local LRU cache. Try to
150 * avoid the expensive remote drain and the
151 * second cache tree walk below by flushing
152 * them out right away.
153 */
154 lru_add_drain();
155
156 count = invalidate_mapping_pages(mapping,
157 start_index, end_index);
158
159 /*
160 * If fewer pages were invalidated than expected then
161 * it is possible that some of the pages were on
162 * a per-cpu pagevec for a remote CPU. Drain all
163 * pagevecs and try again.
164 */
165 if (count < (end_index - start_index + 1)) {
166 lru_add_drain_all();
167 invalidate_mapping_pages(mapping, start_index,
168 end_index);
169 }
170 }
171 break;
172 default:
173 ret = -EINVAL;
174 }
175 out:
176 fdput(f);
177 return ret;
178 }
179
180 #ifdef __ARCH_WANT_SYS_FADVISE64
181
182 SYSCALL_DEFINE4(fadvise64, int, fd, loff_t, offset, size_t, len, int, advice)
183 {
184 return sys_fadvise64_64(fd, offset, len, advice);
185 }
186
187 #endif