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David Howells642fb4d2006-01-06 00:11:41 -08001/* 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>
Dimitri Gorokhovik131612d2006-12-29 16:48:24 -080014#include <linux/mm.h>
David Howells642fb4d2006-01-06 00:11:41 -080015#include <linux/pagemap.h>
16#include <linux/highmem.h>
17#include <linux/init.h>
18#include <linux/string.h>
David Howells642fb4d2006-01-06 00:11:41 -080019#include <linux/backing-dev.h>
20#include <linux/ramfs.h>
David Howells642fb4d2006-01-06 00:11:41 -080021#include <linux/pagevec.h>
22#include <linux/mman.h>
Catalin Marinas5c805362009-07-29 15:04:11 -070023#include <linux/sched.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090024#include <linux/slab.h>
David Howells642fb4d2006-01-06 00:11:41 -080025
26#include <asm/uaccess.h>
27#include "internal.h"
28
29static int ramfs_nommu_setattr(struct dentry *, struct iattr *);
Axel Lin0fa9aa22014-01-23 15:54:54 -080030static 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);
David Howells642fb4d2006-01-06 00:11:41 -080036
Arjan van de Ven4b6f5d22006-03-28 01:56:42 -080037const struct file_operations ramfs_file_operations = {
David Howells642fb4d2006-01-06 00:11:41 -080038 .mmap = ramfs_nommu_mmap,
39 .get_unmapped_area = ramfs_nommu_get_unmapped_area,
Badari Pulavarty543ade12006-09-30 23:28:48 -070040 .read = do_sync_read,
41 .aio_read = generic_file_aio_read,
42 .write = do_sync_write,
43 .aio_write = generic_file_aio_write,
Christoph Hellwig1b061d92010-05-26 17:53:41 +020044 .fsync = noop_fsync,
Jens Axboe5ffc4ef2007-06-01 11:49:19 +020045 .splice_read = generic_file_splice_read,
Octavian Purdila8b3d3562008-07-04 09:33:33 +020046 .splice_write = generic_file_splice_write,
David Howells642fb4d2006-01-06 00:11:41 -080047 .llseek = generic_file_llseek,
48};
49
Arjan van de Venc5ef1c42007-02-12 00:55:40 -080050const struct inode_operations ramfs_file_inode_operations = {
David Howells642fb4d2006-01-06 00:11:41 -080051 .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 */
Nick Piggin4b19de62008-10-02 14:50:16 -070061int ramfs_nommu_expand_for_mapping(struct inode *inode, size_t newsize)
David Howells642fb4d2006-01-06 00:11:41 -080062{
Mike Frysinger0f67b0b2009-12-17 15:27:14 -080063 unsigned long npages, xpages, loop;
David Howells642fb4d2006-01-06 00:11:41 -080064 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))
npiggin@suse.dec08d3b02009-08-21 02:35:06 +100072 return -EFBIG;
David Howells642fb4d2006-01-06 00:11:41 -080073
npiggin@suse.dec08d3b02009-08-21 02:35:06 +100074 ret = inode_newsize_ok(inode, newsize);
75 if (ret)
76 return ret;
David Howells642fb4d2006-01-06 00:11:41 -080077
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
Nick Piggin84097512006-03-22 00:08:34 -080090 split_page(pages, order);
David Howells642fb4d2006-01-06 00:11:41 -080091
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 */
David Howells642fb4d2006-01-06 00:11:41 -0800102 for (loop = 0; loop < npages; loop++) {
103 struct page *page = pages + loop;
104
Johannes Weiner26789582009-03-31 15:23:29 -0700105 ret = add_to_page_cache_lru(page, inode->i_mapping, loop,
106 GFP_KERNEL);
David Howells642fb4d2006-01-06 00:11:41 -0800107 if (ret < 0)
108 goto add_error;
109
Enrik Berkhan020fe222009-03-13 13:51:56 -0700110 /* prevent the page from being discarded on memory pressure */
111 SetPageDirty(page);
Bob Liufea9f712012-07-11 14:02:35 -0700112 SetPageUptodate(page);
Enrik Berkhan020fe222009-03-13 13:51:56 -0700113
David Howells642fb4d2006-01-06 00:11:41 -0800114 unlock_page(page);
Bob Liub836aec2011-04-14 15:22:20 -0700115 put_page(page);
David Howells642fb4d2006-01-06 00:11:41 -0800116 }
117
David Howells642fb4d2006-01-06 00:11:41 -0800118 return 0;
119
npiggin@suse.dec08d3b02009-08-21 02:35:06 +1000120add_error:
Johannes Weiner26789582009-03-31 15:23:29 -0700121 while (loop < npages)
122 __free_page(pages + loop++);
David Howells642fb4d2006-01-06 00:11:41 -0800123 return ret;
124}
125
126/*****************************************************************************/
127/*
David Howells642fb4d2006-01-06 00:11:41 -0800128 *
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) {
David Howells7e660872010-01-15 17:01:39 -0800145 ret = nommu_shrink_inode_mappings(inode, size, newsize);
David Howells642fb4d2006-01-06 00:11:41 -0800146 if (ret < 0)
147 return ret;
148 }
149
Christoph Hellwig2c27c652010-06-04 11:30:04 +0200150 truncate_setsize(inode, newsize);
151 return 0;
David Howells642fb4d2006-01-06 00:11:41 -0800152}
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
Bryan Wu85f60382007-06-05 11:02:01 +0800165 /* POSIX UID/GID verification for setting inode attributes */
166 ret = inode_change_ok(inode, ia);
167 if (ret)
168 return ret;
169
David Howells642fb4d2006-01-06 00:11:41 -0800170 /* pick out size-changing events */
171 if (ia->ia_valid & ATTR_SIZE) {
Nick Piggin3322e792010-05-27 22:42:19 +1000172 loff_t size = inode->i_size;
173
David Howells642fb4d2006-01-06 00:11:41 -0800174 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
Christoph Hellwig6a1a90a2010-06-04 11:30:00 +0200186 setattr_copy(inode, ia);
David Howells642fb4d2006-01-06 00:11:41 -0800187 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 */
Axel Lin0fa9aa22014-01-23 15:54:54 -0800199static unsigned long ramfs_nommu_get_unmapped_area(struct file *file,
David Howells642fb4d2006-01-06 00:11:41 -0800200 unsigned long addr, unsigned long len,
201 unsigned long pgoff, unsigned long flags)
202{
203 unsigned long maxpages, lpages, nr, loop, ret;
Al Viro496ad9a2013-01-23 17:07:38 -0500204 struct inode *inode = file_inode(file);
David Howells642fb4d2006-01-06 00:11:41 -0800205 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)
David Howells0e8f9892009-01-08 12:04:46 +0000227 goto out_free;
David Howells642fb4d2006-01-06 00:11:41 -0800228
229 nr = find_get_pages(inode->i_mapping, pgoff, lpages, pages);
230 if (nr != lpages)
David Howells0e8f9892009-01-08 12:04:46 +0000231 goto out_free_pages; /* leave if some pages were missing */
David Howells642fb4d2006-01-06 00:11:41 -0800232
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++)
David Howells0e8f9892009-01-08 12:04:46 +0000239 goto out_free_pages;
David Howells642fb4d2006-01-06 00:11:41 -0800240
241 /* okay - all conditions fulfilled */
242 ret = (unsigned long) page_address(pages[0]);
243
David Howells0e8f9892009-01-08 12:04:46 +0000244out_free_pages:
245 ptr = pages;
246 for (loop = nr; loop > 0; loop--)
247 put_page(*ptr++);
248out_free:
249 kfree(pages);
250out:
David Howells642fb4d2006-01-06 00:11:41 -0800251 return ret;
252}
253
254/*****************************************************************************/
255/*
David Howells21ff8212006-07-10 04:44:52 -0700256 * set up a mapping for shared memory segments
David Howells642fb4d2006-01-06 00:11:41 -0800257 */
Axel Lin0fa9aa22014-01-23 15:54:54 -0800258static int ramfs_nommu_mmap(struct file *file, struct vm_area_struct *vma)
David Howells642fb4d2006-01-06 00:11:41 -0800259{
David Howells2e92a3b2007-07-31 00:37:24 -0700260 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;
David Howells642fb4d2006-01-06 00:11:41 -0800266}