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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>
14#include <linux/mm.h>
15#include <linux/pagemap.h>
16#include <linux/highmem.h>
17#include <linux/init.h>
18#include <linux/string.h>
19#include <linux/backing-dev.h>
20#include <linux/ramfs.h>
21#include <linux/pagevec.h>
22#include <linux/mman.h>
23#include <linux/sched.h>
24#include <linux/slab.h>
25
26#include <asm/uaccess.h>
27#include "internal.h"
28
29static int ramfs_nommu_setattr(struct dentry *, struct iattr *);
30
31const struct address_space_operations ramfs_aops = {
32 .readpage = simple_readpage,
33 .write_begin = simple_write_begin,
34 .write_end = simple_write_end,
35 .set_page_dirty = __set_page_dirty_no_writeback,
36};
37
38const struct file_operations ramfs_file_operations = {
39 .mmap = ramfs_nommu_mmap,
40 .get_unmapped_area = ramfs_nommu_get_unmapped_area,
41 .read = do_sync_read,
42 .aio_read = generic_file_aio_read,
43 .write = do_sync_write,
44 .aio_write = generic_file_aio_write,
45 .fsync = noop_fsync,
46 .splice_read = generic_file_splice_read,
47 .splice_write = generic_file_splice_write,
48 .llseek = generic_file_llseek,
49};
50
51const struct inode_operations ramfs_file_inode_operations = {
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 */
62int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
63{
64 unsigned long npages, xpages, loop;
65 struct page *pages;
66 unsigned order;
67 void *data;
68 int ret;
69
70 /* make various checks */
71 order = get_order(newsize);
72 if (unlikely(order >= MAX_ORDER))
73 return -EFBIG;
74
75 ret = inode_newsize_ok(inode, newsize);
76 if (ret)
77 return ret;
78
79 i_size_write(inode, newsize);
80
81 /* allocate enough contiguous pages to be able to satisfy the
82 * request */
83 pages = alloc_pages(mapping_gfp_mask(inode->i_mapping), order);
84 if (!pages)
85 return -ENOMEM;
86
87 /* split the high-order page into an array of single pages */
88 xpages = 1UL << order;
89 npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
90
91 split_page(pages, order);
92
93 /* trim off any pages we don't actually require */
94 for (loop = npages; loop < xpages; loop++)
95 __free_page(pages + loop);
96
97 /* clear the memory we allocated */
98 newsize = PAGE_SIZE * npages;
99 data = page_address(pages);
100 memset(data, 0, newsize);
101
102 /* attach all the pages to the inode's address space */
103 for (loop = 0; loop < npages; loop++) {
104 struct page *page = pages + loop;
105
106 ret = add_to_page_cache_lru(page, inode->i_mapping, loop,
107 GFP_KERNEL);
108 if (ret < 0)
109 goto add_error;
110
111 /* prevent the page from being discarded on memory pressure */
112 SetPageDirty(page);
113
114 unlock_page(page);
115 put_page(page);
116 }
117
118 return 0;
119
120add_error:
121 while (loop < npages)
122 __free_page(pages + loop++);
123 return ret;
124}
125
126/*****************************************************************************/
127/*
128 *
129 */
130static int ramfs_nommu_resize(struct inode *inode, loff_t newsize, loff_t size)
131{
132 int ret;
133
134 /* assume a truncate from zero size is going to be for the purposes of
135 * shared mmap */
136 if (size == 0) {
137 if (unlikely(newsize >> 32))
138 return -EFBIG;
139
140 return ramfs_nommu_expand_for_mapping(inode, newsize);
141 }
142
143 /* check that a decrease in size doesn't cut off any shared mappings */
144 if (newsize < size) {
145 ret = nommu_shrink_inode_mappings(inode, size, newsize);
146 if (ret < 0)
147 return ret;
148 }
149
150 truncate_setsize(inode, newsize);
151 return 0;
152}
153
154/*****************************************************************************/
155/*
156 * handle a change of attributes
157 * - we're specifically interested in a change of size
158 */
159static int ramfs_nommu_setattr(struct dentry *dentry, struct iattr *ia)
160{
161 struct inode *inode = dentry->d_inode;
162 unsigned int old_ia_valid = ia->ia_valid;
163 int ret = 0;
164
165 /* POSIX UID/GID verification for setting inode attributes */
166 ret = inode_change_ok(inode, ia);
167 if (ret)
168 return ret;
169
170 /* pick out size-changing events */
171 if (ia->ia_valid & ATTR_SIZE) {
172 loff_t size = inode->i_size;
173
174 if (ia->ia_size != size) {
175 ret = ramfs_nommu_resize(inode, ia->ia_size, size);
176 if (ret < 0 || ia->ia_valid == ATTR_SIZE)
177 goto out;
178 } else {
179 /* we skipped the truncate but must still update
180 * timestamps
181 */
182 ia->ia_valid |= ATTR_MTIME|ATTR_CTIME;
183 }
184 }
185
186 setattr_copy(inode, ia);
187 out:
188 ia->ia_valid = old_ia_valid;
189 return ret;
190}
191
192/*****************************************************************************/
193/*
194 * try to determine where a shared mapping can be made
195 * - we require that:
196 * - the pages to be mapped must exist
197 * - the pages be physically contiguous in sequence
198 */
199unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
200 unsigned long addr, unsigned long len,
201 unsigned long pgoff, unsigned long flags)
202{
203 unsigned long maxpages, lpages, nr, loop, ret;
204 struct inode *inode = file->f_path.dentry->d_inode;
205 struct page **pages = NULL, **ptr, *page;
206 loff_t isize;
207
208 if (!(flags & MAP_SHARED))
209 return addr;
210
211 /* the mapping mustn't extend beyond the EOF */
212 lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
213 isize = i_size_read(inode);
214
215 ret = -EINVAL;
216 maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
217 if (pgoff >= maxpages)
218 goto out;
219
220 if (maxpages - pgoff < lpages)
221 goto out;
222
223 /* gang-find the pages */
224 ret = -ENOMEM;
225 pages = kzalloc(lpages * sizeof(struct page *), GFP_KERNEL);
226 if (!pages)
227 goto out_free;
228
229 nr = find_get_pages(inode->i_mapping, pgoff, lpages, pages);
230 if (nr != lpages)
231 goto out_free_pages; /* leave if some pages were missing */
232
233 /* check the pages for physical adjacency */
234 ptr = pages;
235 page = *ptr++;
236 page++;
237 for (loop = lpages; loop > 1; loop--)
238 if (*ptr++ != page++)
239 goto out_free_pages;
240
241 /* okay - all conditions fulfilled */
242 ret = (unsigned long) page_address(pages[0]);
243
244out_free_pages:
245 ptr = pages;
246 for (loop = nr; loop > 0; loop--)
247 put_page(*ptr++);
248out_free:
249 kfree(pages);
250out:
251 return ret;
252}
253
254/*****************************************************************************/
255/*
256 * set up a mapping for shared memory segments
257 */
258int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma)
259{
260 if (!(vma->vm_flags & VM_SHARED))
261 return -ENOSYS;
262
263 file_accessed(file);
264 vma->vm_ops = &generic_file_vm_ops;
265 return 0;
266}
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>
14#include <linux/mm.h>
15#include <linux/pagemap.h>
16#include <linux/highmem.h>
17#include <linux/init.h>
18#include <linux/string.h>
19#include <linux/backing-dev.h>
20#include <linux/ramfs.h>
21#include <linux/pagevec.h>
22#include <linux/mman.h>
23#include <linux/sched.h>
24#include <linux/slab.h>
25
26#include <asm/uaccess.h>
27#include "internal.h"
28
29static int ramfs_nommu_setattr(struct dentry *, struct iattr *);
30static 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);
35static int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma);
36
37const struct file_operations ramfs_file_operations = {
38 .mmap = ramfs_nommu_mmap,
39 .get_unmapped_area = ramfs_nommu_get_unmapped_area,
40 .read = do_sync_read,
41 .aio_read = generic_file_aio_read,
42 .write = do_sync_write,
43 .aio_write = generic_file_aio_write,
44 .fsync = noop_fsync,
45 .splice_read = generic_file_splice_read,
46 .splice_write = generic_file_splice_write,
47 .llseek = generic_file_llseek,
48};
49
50const struct inode_operations ramfs_file_inode_operations = {
51 .setattr = ramfs_nommu_setattr,
52 .getattr = simple_getattr,
53};
54
55/*****************************************************************************/
56/*
57 * add a contiguous set of pages into a ramfs inode when it's truncated from
58 * size 0 on the assumption that it's going to be used for an mmap of shared
59 * memory
60 */
61int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
62{
63 unsigned long npages, xpages, loop;
64 struct page *pages;
65 unsigned order;
66 void *data;
67 int ret;
68
69 /* make various checks */
70 order = get_order(newsize);
71 if (unlikely(order >= MAX_ORDER))
72 return -EFBIG;
73
74 ret = inode_newsize_ok(inode, newsize);
75 if (ret)
76 return ret;
77
78 i_size_write(inode, newsize);
79
80 /* allocate enough contiguous pages to be able to satisfy the
81 * request */
82 pages = alloc_pages(mapping_gfp_mask(inode->i_mapping), order);
83 if (!pages)
84 return -ENOMEM;
85
86 /* split the high-order page into an array of single pages */
87 xpages = 1UL << order;
88 npages = (newsize + PAGE_SIZE - 1) >> PAGE_SHIFT;
89
90 split_page(pages, order);
91
92 /* trim off any pages we don't actually require */
93 for (loop = npages; loop < xpages; loop++)
94 __free_page(pages + loop);
95
96 /* clear the memory we allocated */
97 newsize = PAGE_SIZE * npages;
98 data = page_address(pages);
99 memset(data, 0, newsize);
100
101 /* attach all the pages to the inode's address space */
102 for (loop = 0; loop < npages; loop++) {
103 struct page *page = pages + loop;
104
105 ret = add_to_page_cache_lru(page, inode->i_mapping, loop,
106 GFP_KERNEL);
107 if (ret < 0)
108 goto add_error;
109
110 /* prevent the page from being discarded on memory pressure */
111 SetPageDirty(page);
112 SetPageUptodate(page);
113
114 unlock_page(page);
115 put_page(page);
116 }
117
118 return 0;
119
120add_error:
121 while (loop < npages)
122 __free_page(pages + loop++);
123 return ret;
124}
125
126/*****************************************************************************/
127/*
128 *
129 */
130static int ramfs_nommu_resize(struct inode *inode, loff_t newsize, loff_t size)
131{
132 int ret;
133
134 /* assume a truncate from zero size is going to be for the purposes of
135 * shared mmap */
136 if (size == 0) {
137 if (unlikely(newsize >> 32))
138 return -EFBIG;
139
140 return ramfs_nommu_expand_for_mapping(inode, newsize);
141 }
142
143 /* check that a decrease in size doesn't cut off any shared mappings */
144 if (newsize < size) {
145 ret = nommu_shrink_inode_mappings(inode, size, newsize);
146 if (ret < 0)
147 return ret;
148 }
149
150 truncate_setsize(inode, newsize);
151 return 0;
152}
153
154/*****************************************************************************/
155/*
156 * handle a change of attributes
157 * - we're specifically interested in a change of size
158 */
159static int ramfs_nommu_setattr(struct dentry *dentry, struct iattr *ia)
160{
161 struct inode *inode = dentry->d_inode;
162 unsigned int old_ia_valid = ia->ia_valid;
163 int ret = 0;
164
165 /* POSIX UID/GID verification for setting inode attributes */
166 ret = inode_change_ok(inode, ia);
167 if (ret)
168 return ret;
169
170 /* pick out size-changing events */
171 if (ia->ia_valid & ATTR_SIZE) {
172 loff_t size = inode->i_size;
173
174 if (ia->ia_size != size) {
175 ret = ramfs_nommu_resize(inode, ia->ia_size, size);
176 if (ret < 0 || ia->ia_valid == ATTR_SIZE)
177 goto out;
178 } else {
179 /* we skipped the truncate but must still update
180 * timestamps
181 */
182 ia->ia_valid |= ATTR_MTIME|ATTR_CTIME;
183 }
184 }
185
186 setattr_copy(inode, ia);
187 out:
188 ia->ia_valid = old_ia_valid;
189 return ret;
190}
191
192/*****************************************************************************/
193/*
194 * try to determine where a shared mapping can be made
195 * - we require that:
196 * - the pages to be mapped must exist
197 * - the pages be physically contiguous in sequence
198 */
199static unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
200 unsigned long addr, unsigned long len,
201 unsigned long pgoff, unsigned long flags)
202{
203 unsigned long maxpages, lpages, nr, loop, ret;
204 struct inode *inode = file_inode(file);
205 struct page **pages = NULL, **ptr, *page;
206 loff_t isize;
207
208 if (!(flags & MAP_SHARED))
209 return addr;
210
211 /* the mapping mustn't extend beyond the EOF */
212 lpages = (len + PAGE_SIZE - 1) >> PAGE_SHIFT;
213 isize = i_size_read(inode);
214
215 ret = -EINVAL;
216 maxpages = (isize + PAGE_SIZE - 1) >> PAGE_SHIFT;
217 if (pgoff >= maxpages)
218 goto out;
219
220 if (maxpages - pgoff < lpages)
221 goto out;
222
223 /* gang-find the pages */
224 ret = -ENOMEM;
225 pages = kzalloc(lpages * sizeof(struct page *), GFP_KERNEL);
226 if (!pages)
227 goto out_free;
228
229 nr = find_get_pages(inode->i_mapping, pgoff, lpages, pages);
230 if (nr != lpages)
231 goto out_free_pages; /* leave if some pages were missing */
232
233 /* check the pages for physical adjacency */
234 ptr = pages;
235 page = *ptr++;
236 page++;
237 for (loop = lpages; loop > 1; loop--)
238 if (*ptr++ != page++)
239 goto out_free_pages;
240
241 /* okay - all conditions fulfilled */
242 ret = (unsigned long) page_address(pages[0]);
243
244out_free_pages:
245 ptr = pages;
246 for (loop = nr; loop > 0; loop--)
247 put_page(*ptr++);
248out_free:
249 kfree(pages);
250out:
251 return ret;
252}
253
254/*****************************************************************************/
255/*
256 * set up a mapping for shared memory segments
257 */
258static int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma)
259{
260 if (!(vma->vm_flags & VM_SHARED))
261 return -ENOSYS;
262
263 file_accessed(file);
264 vma->vm_ops = &generic_file_vm_ops;
265 return 0;
266}