Commit | Line | Data |
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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
642fb4d1 DH |
2 | /* file-nommu.c: no-MMU version of ramfs |
3 | * | |
4 | * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved. | |
5 | * Written by David Howells (dhowells@redhat.com) | |
642fb4d1 DH |
6 | */ |
7 | ||
8 | #include <linux/module.h> | |
9 | #include <linux/fs.h> | |
131612df | 10 | #include <linux/mm.h> |
642fb4d1 DH |
11 | #include <linux/pagemap.h> |
12 | #include <linux/highmem.h> | |
13 | #include <linux/init.h> | |
14 | #include <linux/string.h> | |
642fb4d1 DH |
15 | #include <linux/backing-dev.h> |
16 | #include <linux/ramfs.h> | |
642fb4d1 DH |
17 | #include <linux/pagevec.h> |
18 | #include <linux/mman.h> | |
5c805365 | 19 | #include <linux/sched.h> |
5a0e3ad6 | 20 | #include <linux/slab.h> |
642fb4d1 | 21 | |
7c0f6ba6 | 22 | #include <linux/uaccess.h> |
642fb4d1 DH |
23 | #include "internal.h" |
24 | ||
25 | static int ramfs_nommu_setattr(struct dentry *, struct iattr *); | |
0fa9aa20 AL |
26 | static unsigned long ramfs_nommu_get_unmapped_area(struct file *file, |
27 | unsigned long addr, | |
28 | unsigned long len, | |
29 | unsigned long pgoff, | |
30 | unsigned long flags); | |
31 | static int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma); | |
642fb4d1 | 32 | |
b4caecd4 CH |
33 | static unsigned ramfs_mmap_capabilities(struct file *file) |
34 | { | |
35 | return NOMMU_MAP_DIRECT | NOMMU_MAP_COPY | NOMMU_MAP_READ | | |
36 | NOMMU_MAP_WRITE | NOMMU_MAP_EXEC; | |
37 | } | |
38 | ||
4b6f5d20 | 39 | const struct file_operations ramfs_file_operations = { |
b4caecd4 | 40 | .mmap_capabilities = ramfs_mmap_capabilities, |
642fb4d1 DH |
41 | .mmap = ramfs_nommu_mmap, |
42 | .get_unmapped_area = ramfs_nommu_get_unmapped_area, | |
aad4f8bb | 43 | .read_iter = generic_file_read_iter, |
8174202b | 44 | .write_iter = generic_file_write_iter, |
1b061d92 | 45 | .fsync = noop_fsync, |
5ffc4ef4 | 46 | .splice_read = generic_file_splice_read, |
8d020765 | 47 | .splice_write = iter_file_splice_write, |
642fb4d1 DH |
48 | .llseek = generic_file_llseek, |
49 | }; | |
50 | ||
c5ef1c42 | 51 | const struct inode_operations ramfs_file_inode_operations = { |
642fb4d1 DH |
52 | .setattr = ramfs_nommu_setattr, |
53 | .getattr = simple_getattr, | |
54 | }; | |
55 | ||
56 | /*****************************************************************************/ | |
57 | /* | |
58 | * add a contiguous set of pages into a ramfs inode when it's truncated from | |
59 | * size 0 on the assumption that it's going to be used for an mmap of shared | |
60 | * memory | |
61 | */ | |
4b19de6d | 62 | int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize) |
642fb4d1 | 63 | { |
0f67b0b0 | 64 | unsigned long npages, xpages, loop; |
642fb4d1 DH |
65 | struct page *pages; |
66 | unsigned order; | |
67 | void *data; | |
68 | int ret; | |
063d99b4 | 69 | gfp_t gfp = mapping_gfp_mask(inode->i_mapping); |
642fb4d1 DH |
70 | |
71 | /* make various checks */ | |
72 | order = get_order(newsize); | |
73 | if (unlikely(order >= MAX_ORDER)) | |
c08d3b0e | 74 | return -EFBIG; |
642fb4d1 | 75 | |
c08d3b0e | 76 | ret = inode_newsize_ok(inode, newsize); |
77 | if (ret) | |
78 | return ret; | |
642fb4d1 DH |
79 | |
80 | i_size_write(inode, newsize); | |
81 | ||
82 | /* allocate enough contiguous pages to be able to satisfy the | |
83 | * request */ | |
063d99b4 | 84 | pages = alloc_pages(gfp, order); |
642fb4d1 DH |
85 | if (!pages) |
86 | return -ENOMEM; | |
87 | ||
88 | /* split the high-order page into an array of single pages */ | |
89 | xpages = 1UL << order; | |
90 | npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
91 | ||
84097518 | 92 | split_page(pages, order); |
642fb4d1 DH |
93 | |
94 | /* trim off any pages we don't actually require */ | |
95 | for (loop = npages; loop < xpages; loop++) | |
96 | __free_page(pages + loop); | |
97 | ||
98 | /* clear the memory we allocated */ | |
99 | newsize = PAGE_SIZE * npages; | |
100 | data = page_address(pages); | |
101 | memset(data, 0, newsize); | |
102 | ||
103 | /* attach all the pages to the inode's address space */ | |
642fb4d1 DH |
104 | for (loop = 0; loop < npages; loop++) { |
105 | struct page *page = pages + loop; | |
106 | ||
2678958e | 107 | ret = add_to_page_cache_lru(page, inode->i_mapping, loop, |
063d99b4 | 108 | gfp); |
642fb4d1 DH |
109 | if (ret < 0) |
110 | goto add_error; | |
111 | ||
020fe22f EB |
112 | /* prevent the page from being discarded on memory pressure */ |
113 | SetPageDirty(page); | |
fea9f718 | 114 | SetPageUptodate(page); |
020fe22f | 115 | |
642fb4d1 | 116 | unlock_page(page); |
b836aec5 | 117 | put_page(page); |
642fb4d1 DH |
118 | } |
119 | ||
642fb4d1 DH |
120 | return 0; |
121 | ||
c08d3b0e | 122 | add_error: |
2678958e JW |
123 | while (loop < npages) |
124 | __free_page(pages + loop++); | |
642fb4d1 DH |
125 | return ret; |
126 | } | |
127 | ||
642fb4d1 DH |
128 | /*****************************************************************************/ |
129 | /* | |
130 | * | |
131 | */ | |
132 | static int ramfs_nommu_resize(struct inode *inode, loff_t newsize, loff_t size) | |
133 | { | |
134 | int ret; | |
135 | ||
136 | /* assume a truncate from zero size is going to be for the purposes of | |
137 | * shared mmap */ | |
138 | if (size == 0) { | |
139 | if (unlikely(newsize >> 32)) | |
140 | return -EFBIG; | |
141 | ||
142 | return ramfs_nommu_expand_for_mapping(inode, newsize); | |
143 | } | |
144 | ||
145 | /* check that a decrease in size doesn't cut off any shared mappings */ | |
146 | if (newsize < size) { | |
7e660872 | 147 | ret = nommu_shrink_inode_mappings(inode, size, newsize); |
642fb4d1 DH |
148 | if (ret < 0) |
149 | return ret; | |
150 | } | |
151 | ||
2c27c65e CH |
152 | truncate_setsize(inode, newsize); |
153 | return 0; | |
642fb4d1 DH |
154 | } |
155 | ||
156 | /*****************************************************************************/ | |
157 | /* | |
158 | * handle a change of attributes | |
159 | * - we're specifically interested in a change of size | |
160 | */ | |
161 | static int ramfs_nommu_setattr(struct dentry *dentry, struct iattr *ia) | |
162 | { | |
2b0143b5 | 163 | struct inode *inode = d_inode(dentry); |
642fb4d1 DH |
164 | unsigned int old_ia_valid = ia->ia_valid; |
165 | int ret = 0; | |
166 | ||
85f6038f | 167 | /* POSIX UID/GID verification for setting inode attributes */ |
31051c85 | 168 | ret = setattr_prepare(dentry, ia); |
85f6038f BW |
169 | if (ret) |
170 | return ret; | |
171 | ||
642fb4d1 DH |
172 | /* pick out size-changing events */ |
173 | if (ia->ia_valid & ATTR_SIZE) { | |
3322e79a NP |
174 | loff_t size = inode->i_size; |
175 | ||
642fb4d1 DH |
176 | if (ia->ia_size != size) { |
177 | ret = ramfs_nommu_resize(inode, ia->ia_size, size); | |
178 | if (ret < 0 || ia->ia_valid == ATTR_SIZE) | |
179 | goto out; | |
180 | } else { | |
181 | /* we skipped the truncate but must still update | |
182 | * timestamps | |
183 | */ | |
184 | ia->ia_valid |= ATTR_MTIME|ATTR_CTIME; | |
185 | } | |
186 | } | |
187 | ||
6a1a90ad | 188 | setattr_copy(inode, ia); |
642fb4d1 DH |
189 | out: |
190 | ia->ia_valid = old_ia_valid; | |
191 | return ret; | |
192 | } | |
193 | ||
194 | /*****************************************************************************/ | |
195 | /* | |
196 | * try to determine where a shared mapping can be made | |
197 | * - we require that: | |
198 | * - the pages to be mapped must exist | |
199 | * - the pages be physically contiguous in sequence | |
200 | */ | |
0fa9aa20 | 201 | static unsigned long ramfs_nommu_get_unmapped_area(struct file *file, |
642fb4d1 DH |
202 | unsigned long addr, unsigned long len, |
203 | unsigned long pgoff, unsigned long flags) | |
204 | { | |
205 | unsigned long maxpages, lpages, nr, loop, ret; | |
496ad9aa | 206 | struct inode *inode = file_inode(file); |
642fb4d1 DH |
207 | struct page **pages = NULL, **ptr, *page; |
208 | loff_t isize; | |
209 | ||
642fb4d1 DH |
210 | /* the mapping mustn't extend beyond the EOF */ |
211 | lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT; | |
212 | isize = i_size_read(inode); | |
213 | ||
63678c32 | 214 | ret = -ENOSYS; |
642fb4d1 DH |
215 | maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT; |
216 | if (pgoff >= maxpages) | |
217 | goto out; | |
218 | ||
219 | if (maxpages - pgoff < lpages) | |
220 | goto out; | |
221 | ||
222 | /* gang-find the pages */ | |
6f4535ed | 223 | pages = kcalloc(lpages, sizeof(struct page *), GFP_KERNEL); |
642fb4d1 | 224 | if (!pages) |
0e8f989a | 225 | goto out_free; |
642fb4d1 | 226 | |
d72dc8a2 | 227 | nr = find_get_pages(inode->i_mapping, &pgoff, lpages, pages); |
642fb4d1 | 228 | if (nr != lpages) |
0e8f989a | 229 | goto out_free_pages; /* leave if some pages were missing */ |
642fb4d1 DH |
230 | |
231 | /* check the pages for physical adjacency */ | |
232 | ptr = pages; | |
233 | page = *ptr++; | |
234 | page++; | |
235 | for (loop = lpages; loop > 1; loop--) | |
236 | if (*ptr++ != page++) | |
0e8f989a | 237 | goto out_free_pages; |
642fb4d1 DH |
238 | |
239 | /* okay - all conditions fulfilled */ | |
240 | ret = (unsigned long) page_address(pages[0]); | |
241 | ||
0e8f989a DH |
242 | out_free_pages: |
243 | ptr = pages; | |
244 | for (loop = nr; loop > 0; loop--) | |
245 | put_page(*ptr++); | |
246 | out_free: | |
247 | kfree(pages); | |
248 | out: | |
642fb4d1 DH |
249 | return ret; |
250 | } | |
251 | ||
252 | /*****************************************************************************/ | |
253 | /* | |
21ff8216 | 254 | * set up a mapping for shared memory segments |
642fb4d1 | 255 | */ |
0fa9aa20 | 256 | static int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma) |
642fb4d1 | 257 | { |
63678c32 | 258 | if (!(vma->vm_flags & (VM_SHARED | VM_MAYSHARE))) |
2e92a3ba DH |
259 | return -ENOSYS; |
260 | ||
261 | file_accessed(file); | |
262 | vma->vm_ops = &generic_file_vm_ops; | |
263 | return 0; | |
642fb4d1 | 264 | } |