Commit | Line | Data |
---|---|---|
1da177e4 LT |
1 | /* |
2 | * linux/mm/madvise.c | |
3 | * | |
4 | * Copyright (C) 1999 Linus Torvalds | |
5 | * Copyright (C) 2002 Christoph Hellwig | |
6 | */ | |
7 | ||
8 | #include <linux/mman.h> | |
9 | #include <linux/pagemap.h> | |
10 | #include <linux/syscalls.h> | |
05b74384 | 11 | #include <linux/mempolicy.h> |
1da177e4 LT |
12 | #include <linux/hugetlb.h> |
13 | ||
14 | /* | |
15 | * We can potentially split a vm area into separate | |
16 | * areas, each area with its own behavior. | |
17 | */ | |
05b74384 PM |
18 | static long madvise_behavior(struct vm_area_struct * vma, |
19 | struct vm_area_struct **prev, | |
20 | unsigned long start, unsigned long end, int behavior) | |
1da177e4 LT |
21 | { |
22 | struct mm_struct * mm = vma->vm_mm; | |
23 | int error = 0; | |
05b74384 | 24 | pgoff_t pgoff; |
e798c6e8 PM |
25 | int new_flags = vma->vm_flags & ~VM_READHINTMASK; |
26 | ||
27 | switch (behavior) { | |
28 | case MADV_SEQUENTIAL: | |
29 | new_flags |= VM_SEQ_READ; | |
30 | break; | |
31 | case MADV_RANDOM: | |
32 | new_flags |= VM_RAND_READ; | |
33 | break; | |
34 | default: | |
35 | break; | |
36 | } | |
37 | ||
05b74384 PM |
38 | if (new_flags == vma->vm_flags) { |
39 | *prev = vma; | |
836d5ffd | 40 | goto out; |
05b74384 PM |
41 | } |
42 | ||
43 | pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT); | |
44 | *prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma, | |
45 | vma->vm_file, pgoff, vma_policy(vma)); | |
46 | if (*prev) { | |
47 | vma = *prev; | |
48 | goto success; | |
49 | } | |
50 | ||
51 | *prev = vma; | |
1da177e4 LT |
52 | |
53 | if (start != vma->vm_start) { | |
54 | error = split_vma(mm, vma, start, 1); | |
55 | if (error) | |
56 | goto out; | |
57 | } | |
58 | ||
59 | if (end != vma->vm_end) { | |
60 | error = split_vma(mm, vma, end, 0); | |
61 | if (error) | |
62 | goto out; | |
63 | } | |
64 | ||
836d5ffd | 65 | success: |
1da177e4 LT |
66 | /* |
67 | * vm_flags is protected by the mmap_sem held in write mode. | |
68 | */ | |
e798c6e8 | 69 | vma->vm_flags = new_flags; |
1da177e4 LT |
70 | |
71 | out: | |
72 | if (error == -ENOMEM) | |
73 | error = -EAGAIN; | |
74 | return error; | |
75 | } | |
76 | ||
77 | /* | |
78 | * Schedule all required I/O operations. Do not wait for completion. | |
79 | */ | |
80 | static long madvise_willneed(struct vm_area_struct * vma, | |
05b74384 | 81 | struct vm_area_struct ** prev, |
1da177e4 LT |
82 | unsigned long start, unsigned long end) |
83 | { | |
84 | struct file *file = vma->vm_file; | |
85 | ||
1bef4003 S |
86 | if (!file) |
87 | return -EBADF; | |
88 | ||
fe77ba6f CO |
89 | if (file->f_mapping->a_ops->get_xip_page) { |
90 | /* no bad return value, but ignore advice */ | |
91 | return 0; | |
92 | } | |
93 | ||
05b74384 | 94 | *prev = vma; |
1da177e4 LT |
95 | start = ((start - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; |
96 | if (end > vma->vm_end) | |
97 | end = vma->vm_end; | |
98 | end = ((end - vma->vm_start) >> PAGE_SHIFT) + vma->vm_pgoff; | |
99 | ||
100 | force_page_cache_readahead(file->f_mapping, | |
101 | file, start, max_sane_readahead(end - start)); | |
102 | return 0; | |
103 | } | |
104 | ||
105 | /* | |
106 | * Application no longer needs these pages. If the pages are dirty, | |
107 | * it's OK to just throw them away. The app will be more careful about | |
108 | * data it wants to keep. Be sure to free swap resources too. The | |
109 | * zap_page_range call sets things up for refill_inactive to actually free | |
110 | * these pages later if no one else has touched them in the meantime, | |
111 | * although we could add these pages to a global reuse list for | |
112 | * refill_inactive to pick up before reclaiming other pages. | |
113 | * | |
114 | * NB: This interface discards data rather than pushes it out to swap, | |
115 | * as some implementations do. This has performance implications for | |
116 | * applications like large transactional databases which want to discard | |
117 | * pages in anonymous maps after committing to backing store the data | |
118 | * that was kept in them. There is no reason to write this data out to | |
119 | * the swap area if the application is discarding it. | |
120 | * | |
121 | * An interface that causes the system to free clean pages and flush | |
122 | * dirty pages is already available as msync(MS_INVALIDATE). | |
123 | */ | |
124 | static long madvise_dontneed(struct vm_area_struct * vma, | |
05b74384 | 125 | struct vm_area_struct ** prev, |
1da177e4 LT |
126 | unsigned long start, unsigned long end) |
127 | { | |
05b74384 | 128 | *prev = vma; |
6aab341e | 129 | if (vma->vm_flags & (VM_LOCKED|VM_HUGETLB|VM_PFNMAP)) |
1da177e4 LT |
130 | return -EINVAL; |
131 | ||
132 | if (unlikely(vma->vm_flags & VM_NONLINEAR)) { | |
133 | struct zap_details details = { | |
134 | .nonlinear_vma = vma, | |
135 | .last_index = ULONG_MAX, | |
136 | }; | |
137 | zap_page_range(vma, start, end - start, &details); | |
138 | } else | |
139 | zap_page_range(vma, start, end - start, NULL); | |
140 | return 0; | |
141 | } | |
142 | ||
f6b3ec23 BP |
143 | /* |
144 | * Application wants to free up the pages and associated backing store. | |
145 | * This is effectively punching a hole into the middle of a file. | |
146 | * | |
147 | * NOTE: Currently, only shmfs/tmpfs is supported for this operation. | |
148 | * Other filesystems return -ENOSYS. | |
149 | */ | |
150 | static long madvise_remove(struct vm_area_struct *vma, | |
151 | unsigned long start, unsigned long end) | |
152 | { | |
153 | struct address_space *mapping; | |
154 | loff_t offset, endoff; | |
155 | ||
156 | if (vma->vm_flags & (VM_LOCKED|VM_NONLINEAR|VM_HUGETLB)) | |
157 | return -EINVAL; | |
158 | ||
159 | if (!vma->vm_file || !vma->vm_file->f_mapping | |
160 | || !vma->vm_file->f_mapping->host) { | |
161 | return -EINVAL; | |
162 | } | |
163 | ||
164 | mapping = vma->vm_file->f_mapping; | |
165 | ||
166 | offset = (loff_t)(start - vma->vm_start) | |
167 | + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); | |
168 | endoff = (loff_t)(end - vma->vm_start - 1) | |
169 | + ((loff_t)vma->vm_pgoff << PAGE_SHIFT); | |
170 | return vmtruncate_range(mapping->host, offset, endoff); | |
171 | } | |
172 | ||
165cd402 | 173 | static long |
174 | madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev, | |
175 | unsigned long start, unsigned long end, int behavior) | |
1da177e4 | 176 | { |
1bef4003 | 177 | long error; |
165cd402 | 178 | |
1da177e4 LT |
179 | switch (behavior) { |
180 | case MADV_NORMAL: | |
181 | case MADV_SEQUENTIAL: | |
182 | case MADV_RANDOM: | |
05b74384 | 183 | error = madvise_behavior(vma, prev, start, end, behavior); |
1da177e4 | 184 | break; |
f6b3ec23 BP |
185 | case MADV_REMOVE: |
186 | error = madvise_remove(vma, start, end); | |
187 | break; | |
1da177e4 LT |
188 | |
189 | case MADV_WILLNEED: | |
05b74384 | 190 | error = madvise_willneed(vma, prev, start, end); |
1da177e4 LT |
191 | break; |
192 | ||
193 | case MADV_DONTNEED: | |
05b74384 | 194 | error = madvise_dontneed(vma, prev, start, end); |
1da177e4 LT |
195 | break; |
196 | ||
197 | default: | |
198 | error = -EINVAL; | |
199 | break; | |
200 | } | |
1da177e4 LT |
201 | return error; |
202 | } | |
203 | ||
204 | /* | |
205 | * The madvise(2) system call. | |
206 | * | |
207 | * Applications can use madvise() to advise the kernel how it should | |
208 | * handle paging I/O in this VM area. The idea is to help the kernel | |
209 | * use appropriate read-ahead and caching techniques. The information | |
210 | * provided is advisory only, and can be safely disregarded by the | |
211 | * kernel without affecting the correct operation of the application. | |
212 | * | |
213 | * behavior values: | |
214 | * MADV_NORMAL - the default behavior is to read clusters. This | |
215 | * results in some read-ahead and read-behind. | |
216 | * MADV_RANDOM - the system should read the minimum amount of data | |
217 | * on any access, since it is unlikely that the appli- | |
218 | * cation will need more than what it asks for. | |
219 | * MADV_SEQUENTIAL - pages in the given range will probably be accessed | |
220 | * once, so they can be aggressively read ahead, and | |
221 | * can be freed soon after they are accessed. | |
222 | * MADV_WILLNEED - the application is notifying the system to read | |
223 | * some pages ahead. | |
224 | * MADV_DONTNEED - the application is finished with the given range, | |
225 | * so the kernel can free resources associated with it. | |
f6b3ec23 BP |
226 | * MADV_REMOVE - the application wants to free up the given range of |
227 | * pages and associated backing store. | |
1da177e4 LT |
228 | * |
229 | * return values: | |
230 | * zero - success | |
231 | * -EINVAL - start + len < 0, start is not page-aligned, | |
232 | * "behavior" is not a valid value, or application | |
233 | * is attempting to release locked or shared pages. | |
234 | * -ENOMEM - addresses in the specified range are not currently | |
235 | * mapped, or are outside the AS of the process. | |
236 | * -EIO - an I/O error occurred while paging in data. | |
237 | * -EBADF - map exists, but area maps something that isn't a file. | |
238 | * -EAGAIN - a kernel resource was temporarily unavailable. | |
239 | */ | |
240 | asmlinkage long sys_madvise(unsigned long start, size_t len_in, int behavior) | |
241 | { | |
05b74384 PM |
242 | unsigned long end, tmp; |
243 | struct vm_area_struct * vma, *prev; | |
1da177e4 LT |
244 | int unmapped_error = 0; |
245 | int error = -EINVAL; | |
246 | size_t len; | |
247 | ||
248 | down_write(¤t->mm->mmap_sem); | |
249 | ||
250 | if (start & ~PAGE_MASK) | |
251 | goto out; | |
252 | len = (len_in + ~PAGE_MASK) & PAGE_MASK; | |
253 | ||
254 | /* Check to see whether len was rounded up from small -ve to zero */ | |
255 | if (len_in && !len) | |
256 | goto out; | |
257 | ||
258 | end = start + len; | |
259 | if (end < start) | |
260 | goto out; | |
261 | ||
262 | error = 0; | |
263 | if (end == start) | |
264 | goto out; | |
265 | ||
266 | /* | |
267 | * If the interval [start,end) covers some unmapped address | |
268 | * ranges, just ignore them, but return -ENOMEM at the end. | |
05b74384 | 269 | * - different from the way of handling in mlock etc. |
1da177e4 | 270 | */ |
05b74384 | 271 | vma = find_vma_prev(current->mm, start, &prev); |
836d5ffd HD |
272 | if (vma && start > vma->vm_start) |
273 | prev = vma; | |
274 | ||
1da177e4 LT |
275 | for (;;) { |
276 | /* Still start < end. */ | |
277 | error = -ENOMEM; | |
278 | if (!vma) | |
279 | goto out; | |
280 | ||
05b74384 | 281 | /* Here start < (end|vma->vm_end). */ |
1da177e4 LT |
282 | if (start < vma->vm_start) { |
283 | unmapped_error = -ENOMEM; | |
284 | start = vma->vm_start; | |
05b74384 PM |
285 | if (start >= end) |
286 | goto out; | |
1da177e4 LT |
287 | } |
288 | ||
05b74384 PM |
289 | /* Here vma->vm_start <= start < (end|vma->vm_end) */ |
290 | tmp = vma->vm_end; | |
291 | if (end < tmp) | |
292 | tmp = end; | |
1da177e4 | 293 | |
05b74384 PM |
294 | /* Here vma->vm_start <= start < tmp <= (end|vma->vm_end). */ |
295 | error = madvise_vma(vma, &prev, start, tmp, behavior); | |
1da177e4 LT |
296 | if (error) |
297 | goto out; | |
05b74384 PM |
298 | start = tmp; |
299 | if (start < prev->vm_end) | |
300 | start = prev->vm_end; | |
301 | error = unmapped_error; | |
302 | if (start >= end) | |
303 | goto out; | |
304 | vma = prev->vm_next; | |
1da177e4 | 305 | } |
1da177e4 LT |
306 | out: |
307 | up_write(¤t->mm->mmap_sem); | |
308 | return error; | |
309 | } |