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642fb4d1 DH |
1 | /* file-nommu.c: no-MMU version of ramfs |
2 | * | |
3 | * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved. | |
4 | * Written by David Howells (dhowells@redhat.com) | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/module.h> | |
13 | #include <linux/fs.h> | |
131612df | 14 | #include <linux/mm.h> |
642fb4d1 DH |
15 | #include <linux/pagemap.h> |
16 | #include <linux/highmem.h> | |
17 | #include <linux/init.h> | |
18 | #include <linux/string.h> | |
642fb4d1 DH |
19 | #include <linux/backing-dev.h> |
20 | #include <linux/ramfs.h> | |
642fb4d1 DH |
21 | #include <linux/pagevec.h> |
22 | #include <linux/mman.h> | |
5c805365 | 23 | #include <linux/sched.h> |
5a0e3ad6 | 24 | #include <linux/slab.h> |
642fb4d1 DH |
25 | |
26 | #include <asm/uaccess.h> | |
27 | #include "internal.h" | |
28 | ||
29 | static int ramfs_nommu_setattr(struct dentry *, struct iattr *); | |
0fa9aa20 AL |
30 | static unsigned long ramfs_nommu_get_unmapped_area(struct file *file, |
31 | unsigned long addr, | |
32 | unsigned long len, | |
33 | unsigned long pgoff, | |
34 | unsigned long flags); | |
35 | static int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma); | |
642fb4d1 | 36 | |
b4caecd4 CH |
37 | static unsigned ramfs_mmap_capabilities(struct file *file) |
38 | { | |
39 | return NOMMU_MAP_DIRECT | NOMMU_MAP_COPY | NOMMU_MAP_READ | | |
40 | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC; | |
41 | } | |
42 | ||
4b6f5d20 | 43 | const struct file_operations ramfs_file_operations = { |
b4caecd4 | 44 | .mmap_capabilities = ramfs_mmap_capabilities, |
642fb4d1 DH |
45 | .mmap = ramfs_nommu_mmap, |
46 | .get_unmapped_area = ramfs_nommu_get_unmapped_area, | |
aad4f8bb | 47 | .read_iter = generic_file_read_iter, |
8174202b | 48 | .write_iter = generic_file_write_iter, |
1b061d92 | 49 | .fsync = noop_fsync, |
5ffc4ef4 | 50 | .splice_read = generic_file_splice_read, |
8d020765 | 51 | .splice_write = iter_file_splice_write, |
642fb4d1 DH |
52 | .llseek = generic_file_llseek, |
53 | }; | |
54 | ||
c5ef1c42 | 55 | const struct inode_operations ramfs_file_inode_operations = { |
642fb4d1 DH |
56 | .setattr = ramfs_nommu_setattr, |
57 | .getattr = simple_getattr, | |
58 | }; | |
59 | ||
60 | /*****************************************************************************/ | |
61 | /* | |
62 | * add a contiguous set of pages into a ramfs inode when it's truncated from | |
63 | * size 0 on the assumption that it's going to be used for an mmap of shared | |
64 | * memory | |
65 | */ | |
4b19de6d | 66 | int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize) |
642fb4d1 | 67 | { |
0f67b0b0 | 68 | unsigned long npages, xpages, loop; |
642fb4d1 DH |
69 | struct page *pages; |
70 | unsigned order; | |
71 | void *data; | |
72 | int ret; | |
73 | ||
74 | /* make various checks */ | |
75 | order = get_order(newsize); | |
76 | if (unlikely(order >= MAX_ORDER)) | |
c08d3b0e | 77 | return -EFBIG; |
642fb4d1 | 78 | |
c08d3b0e | 79 | ret = inode_newsize_ok(inode, newsize); |
80 | if (ret) | |
81 | return ret; | |
642fb4d1 DH |
82 | |
83 | i_size_write(inode, newsize); | |
84 | ||
85 | /* allocate enough contiguous pages to be able to satisfy the | |
86 | * request */ | |
87 | pages = alloc_pages(mapping_gfp_mask(inode->i_mapping), order); | |
88 | if (!pages) | |
89 | return -ENOMEM; | |
90 | ||
91 | /* split the high-order page into an array of single pages */ | |
92 | xpages = 1UL << order; | |
93 | npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
94 | ||
84097518 | 95 | split_page(pages, order); |
642fb4d1 DH |
96 | |
97 | /* trim off any pages we don't actually require */ | |
98 | for (loop = npages; loop < xpages; loop++) | |
99 | __free_page(pages + loop); | |
100 | ||
101 | /* clear the memory we allocated */ | |
102 | newsize = PAGE_SIZE * npages; | |
103 | data = page_address(pages); | |
104 | memset(data, 0, newsize); | |
105 | ||
106 | /* attach all the pages to the inode's address space */ | |
642fb4d1 DH |
107 | for (loop = 0; loop < npages; loop++) { |
108 | struct page *page = pages + loop; | |
109 | ||
2678958e JW |
110 | ret = add_to_page_cache_lru(page, inode->i_mapping, loop, |
111 | GFP_KERNEL); | |
642fb4d1 DH |
112 | if (ret < 0) |
113 | goto add_error; | |
114 | ||
020fe22f EB |
115 | /* prevent the page from being discarded on memory pressure */ |
116 | SetPageDirty(page); | |
fea9f718 | 117 | SetPageUptodate(page); |
020fe22f | 118 | |
642fb4d1 | 119 | unlock_page(page); |
b836aec5 | 120 | put_page(page); |
642fb4d1 DH |
121 | } |
122 | ||
642fb4d1 DH |
123 | return 0; |
124 | ||
c08d3b0e | 125 | add_error: |
2678958e JW |
126 | while (loop < npages) |
127 | __free_page(pages + loop++); | |
642fb4d1 DH |
128 | return ret; |
129 | } | |
130 | ||
642fb4d1 DH |
131 | /*****************************************************************************/ |
132 | /* | |
133 | * | |
134 | */ | |
135 | static int ramfs_nommu_resize(struct inode *inode, loff_t newsize, loff_t size) | |
136 | { | |
137 | int ret; | |
138 | ||
139 | /* assume a truncate from zero size is going to be for the purposes of | |
140 | * shared mmap */ | |
141 | if (size == 0) { | |
142 | if (unlikely(newsize >> 32)) | |
143 | return -EFBIG; | |
144 | ||
145 | return ramfs_nommu_expand_for_mapping(inode, newsize); | |
146 | } | |
147 | ||
148 | /* check that a decrease in size doesn't cut off any shared mappings */ | |
149 | if (newsize < size) { | |
7e660872 | 150 | ret = nommu_shrink_inode_mappings(inode, size, newsize); |
642fb4d1 DH |
151 | if (ret < 0) |
152 | return ret; | |
153 | } | |
154 | ||
2c27c65e CH |
155 | truncate_setsize(inode, newsize); |
156 | return 0; | |
642fb4d1 DH |
157 | } |
158 | ||
159 | /*****************************************************************************/ | |
160 | /* | |
161 | * handle a change of attributes | |
162 | * - we're specifically interested in a change of size | |
163 | */ | |
164 | static int ramfs_nommu_setattr(struct dentry *dentry, struct iattr *ia) | |
165 | { | |
2b0143b5 | 166 | struct inode *inode = d_inode(dentry); |
642fb4d1 DH |
167 | unsigned int old_ia_valid = ia->ia_valid; |
168 | int ret = 0; | |
169 | ||
85f6038f BW |
170 | /* POSIX UID/GID verification for setting inode attributes */ |
171 | ret = inode_change_ok(inode, ia); | |
172 | if (ret) | |
173 | return ret; | |
174 | ||
642fb4d1 DH |
175 | /* pick out size-changing events */ |
176 | if (ia->ia_valid & ATTR_SIZE) { | |
3322e79a NP |
177 | loff_t size = inode->i_size; |
178 | ||
642fb4d1 DH |
179 | if (ia->ia_size != size) { |
180 | ret = ramfs_nommu_resize(inode, ia->ia_size, size); | |
181 | if (ret < 0 || ia->ia_valid == ATTR_SIZE) | |
182 | goto out; | |
183 | } else { | |
184 | /* we skipped the truncate but must still update | |
185 | * timestamps | |
186 | */ | |
187 | ia->ia_valid |= ATTR_MTIME|ATTR_CTIME; | |
188 | } | |
189 | } | |
190 | ||
6a1a90ad | 191 | setattr_copy(inode, ia); |
642fb4d1 DH |
192 | out: |
193 | ia->ia_valid = old_ia_valid; | |
194 | return ret; | |
195 | } | |
196 | ||
197 | /*****************************************************************************/ | |
198 | /* | |
199 | * try to determine where a shared mapping can be made | |
200 | * - we require that: | |
201 | * - the pages to be mapped must exist | |
202 | * - the pages be physically contiguous in sequence | |
203 | */ | |
0fa9aa20 | 204 | static unsigned long ramfs_nommu_get_unmapped_area(struct file *file, |
642fb4d1 DH |
205 | unsigned long addr, unsigned long len, |
206 | unsigned long pgoff, unsigned long flags) | |
207 | { | |
208 | unsigned long maxpages, lpages, nr, loop, ret; | |
496ad9aa | 209 | struct inode *inode = file_inode(file); |
642fb4d1 DH |
210 | struct page **pages = NULL, **ptr, *page; |
211 | loff_t isize; | |
212 | ||
213 | if (!(flags & MAP_SHARED)) | |
214 | return addr; | |
215 | ||
216 | /* the mapping mustn't extend beyond the EOF */ | |
217 | lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
218 | isize = i_size_read(inode); | |
219 | ||
220 | ret = -EINVAL; | |
221 | maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
222 | if (pgoff >= maxpages) | |
223 | goto out; | |
224 | ||
225 | if (maxpages - pgoff < lpages) | |
226 | goto out; | |
227 | ||
228 | /* gang-find the pages */ | |
229 | ret = -ENOMEM; | |
6f4535ed | 230 | pages = kcalloc(lpages, sizeof(struct page *), GFP_KERNEL); |
642fb4d1 | 231 | if (!pages) |
0e8f989a | 232 | goto out_free; |
642fb4d1 DH |
233 | |
234 | nr = find_get_pages(inode->i_mapping, pgoff, lpages, pages); | |
235 | if (nr != lpages) | |
0e8f989a | 236 | goto out_free_pages; /* leave if some pages were missing */ |
642fb4d1 DH |
237 | |
238 | /* check the pages for physical adjacency */ | |
239 | ptr = pages; | |
240 | page = *ptr++; | |
241 | page++; | |
242 | for (loop = lpages; loop > 1; loop--) | |
243 | if (*ptr++ != page++) | |
0e8f989a | 244 | goto out_free_pages; |
642fb4d1 DH |
245 | |
246 | /* okay - all conditions fulfilled */ | |
247 | ret = (unsigned long) page_address(pages[0]); | |
248 | ||
0e8f989a DH |
249 | out_free_pages: |
250 | ptr = pages; | |
251 | for (loop = nr; loop > 0; loop--) | |
252 | put_page(*ptr++); | |
253 | out_free: | |
254 | kfree(pages); | |
255 | out: | |
642fb4d1 DH |
256 | return ret; |
257 | } | |
258 | ||
259 | /*****************************************************************************/ | |
260 | /* | |
21ff8216 | 261 | * set up a mapping for shared memory segments |
642fb4d1 | 262 | */ |
0fa9aa20 | 263 | static int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma) |
642fb4d1 | 264 | { |
2e92a3ba DH |
265 | if (!(vma->vm_flags & VM_SHARED)) |
266 | return -ENOSYS; | |
267 | ||
268 | file_accessed(file); | |
269 | vma->vm_ops = &generic_file_vm_ops; | |
270 | return 0; | |
642fb4d1 | 271 | } |