1 /* file-nommu.c: no-MMU version of ramfs
3 * Copyright (C) 2005 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells (dhowells@redhat.com)
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.
12 #include <linux/module.h>
14 #include <linux/pagemap.h>
15 #include <linux/highmem.h>
16 #include <linux/init.h>
17 #include <linux/string.h>
18 #include <linux/smp_lock.h>
19 #include <linux/backing-dev.h>
20 #include <linux/ramfs.h>
21 #include <linux/quotaops.h>
22 #include <linux/pagevec.h>
23 #include <linux/mman.h>
25 #include <asm/uaccess.h>
28 static int ramfs_nommu_setattr(struct dentry
*, struct iattr
*);
30 const struct address_space_operations ramfs_aops
= {
31 .readpage
= simple_readpage
,
32 .prepare_write
= simple_prepare_write
,
33 .commit_write
= simple_commit_write
36 const struct file_operations ramfs_file_operations
= {
37 .mmap
= ramfs_nommu_mmap
,
38 .get_unmapped_area
= ramfs_nommu_get_unmapped_area
,
40 .aio_read
= generic_file_aio_read
,
41 .write
= do_sync_write
,
42 .aio_write
= generic_file_aio_write
,
43 .fsync
= simple_sync_file
,
44 .sendfile
= generic_file_sendfile
,
45 .llseek
= generic_file_llseek
,
48 struct inode_operations ramfs_file_inode_operations
= {
49 .setattr
= ramfs_nommu_setattr
,
50 .getattr
= simple_getattr
,
53 /*****************************************************************************/
55 * add a contiguous set of pages into a ramfs inode when it's truncated from
56 * size 0 on the assumption that it's going to be used for an mmap of shared
59 static int ramfs_nommu_expand_for_mapping(struct inode
*inode
, size_t newsize
)
61 struct pagevec lru_pvec
;
62 unsigned long npages
, xpages
, loop
, limit
;
68 /* make various checks */
69 order
= get_order(newsize
);
70 if (unlikely(order
>= MAX_ORDER
))
73 limit
= current
->signal
->rlim
[RLIMIT_FSIZE
].rlim_cur
;
74 if (limit
!= RLIM_INFINITY
&& newsize
> limit
)
77 if (newsize
> inode
->i_sb
->s_maxbytes
)
80 i_size_write(inode
, newsize
);
82 /* allocate enough contiguous pages to be able to satisfy the
84 pages
= alloc_pages(mapping_gfp_mask(inode
->i_mapping
), order
);
88 /* split the high-order page into an array of single pages */
89 xpages
= 1UL << order
;
90 npages
= (newsize
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
92 split_page(pages
, order
);
94 /* trim off any pages we don't actually require */
95 for (loop
= npages
; loop
< xpages
; loop
++)
96 __free_page(pages
+ loop
);
98 /* clear the memory we allocated */
99 newsize
= PAGE_SIZE
* npages
;
100 data
= page_address(pages
);
101 memset(data
, 0, newsize
);
103 /* attach all the pages to the inode's address space */
104 pagevec_init(&lru_pvec
, 0);
105 for (loop
= 0; loop
< npages
; loop
++) {
106 struct page
*page
= pages
+ loop
;
108 ret
= add_to_page_cache(page
, inode
->i_mapping
, loop
, GFP_KERNEL
);
112 if (!pagevec_add(&lru_pvec
, page
))
113 __pagevec_lru_add(&lru_pvec
);
118 pagevec_lru_add(&lru_pvec
);
122 send_sig(SIGXFSZ
, current
, 0);
127 page_cache_release(pages
+ loop
);
128 for (loop
++; loop
< npages
; loop
++)
129 __free_page(pages
+ loop
);
133 /*****************************************************************************/
135 * check that file shrinkage doesn't leave any VMAs dangling in midair
137 static int ramfs_nommu_check_mappings(struct inode
*inode
,
138 size_t newsize
, size_t size
)
140 struct vm_area_struct
*vma
;
141 struct prio_tree_iter iter
;
143 /* search for VMAs that fall within the dead zone */
144 vma_prio_tree_foreach(vma
, &iter
, &inode
->i_mapping
->i_mmap
,
145 newsize
>> PAGE_SHIFT
,
146 (size
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
148 /* found one - only interested if it's shared out of the page
150 if (vma
->vm_flags
& VM_SHARED
)
151 return -ETXTBSY
; /* not quite true, but near enough */
157 /*****************************************************************************/
161 static int ramfs_nommu_resize(struct inode
*inode
, loff_t newsize
, loff_t size
)
165 /* assume a truncate from zero size is going to be for the purposes of
168 if (unlikely(newsize
>> 32))
171 return ramfs_nommu_expand_for_mapping(inode
, newsize
);
174 /* check that a decrease in size doesn't cut off any shared mappings */
175 if (newsize
< size
) {
176 ret
= ramfs_nommu_check_mappings(inode
, newsize
, size
);
181 ret
= vmtruncate(inode
, size
);
186 /*****************************************************************************/
188 * handle a change of attributes
189 * - we're specifically interested in a change of size
191 static int ramfs_nommu_setattr(struct dentry
*dentry
, struct iattr
*ia
)
193 struct inode
*inode
= dentry
->d_inode
;
194 unsigned int old_ia_valid
= ia
->ia_valid
;
197 /* by providing our own setattr() method, we skip this quotaism */
198 if ((old_ia_valid
& ATTR_UID
&& ia
->ia_uid
!= inode
->i_uid
) ||
199 (old_ia_valid
& ATTR_GID
&& ia
->ia_gid
!= inode
->i_gid
))
200 ret
= DQUOT_TRANSFER(inode
, ia
) ? -EDQUOT
: 0;
202 /* pick out size-changing events */
203 if (ia
->ia_valid
& ATTR_SIZE
) {
204 loff_t size
= i_size_read(inode
);
205 if (ia
->ia_size
!= size
) {
206 ret
= ramfs_nommu_resize(inode
, ia
->ia_size
, size
);
207 if (ret
< 0 || ia
->ia_valid
== ATTR_SIZE
)
210 /* we skipped the truncate but must still update
213 ia
->ia_valid
|= ATTR_MTIME
|ATTR_CTIME
;
217 ret
= inode_setattr(inode
, ia
);
219 ia
->ia_valid
= old_ia_valid
;
223 /*****************************************************************************/
225 * try to determine where a shared mapping can be made
227 * - the pages to be mapped must exist
228 * - the pages be physically contiguous in sequence
230 unsigned long ramfs_nommu_get_unmapped_area(struct file
*file
,
231 unsigned long addr
, unsigned long len
,
232 unsigned long pgoff
, unsigned long flags
)
234 unsigned long maxpages
, lpages
, nr
, loop
, ret
;
235 struct inode
*inode
= file
->f_dentry
->d_inode
;
236 struct page
**pages
= NULL
, **ptr
, *page
;
239 if (!(flags
& MAP_SHARED
))
242 /* the mapping mustn't extend beyond the EOF */
243 lpages
= (len
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
244 isize
= i_size_read(inode
);
247 maxpages
= (isize
+ PAGE_SIZE
- 1) >> PAGE_SHIFT
;
248 if (pgoff
>= maxpages
)
251 if (maxpages
- pgoff
< lpages
)
254 /* gang-find the pages */
256 pages
= kzalloc(lpages
* sizeof(struct page
*), GFP_KERNEL
);
260 nr
= find_get_pages(inode
->i_mapping
, pgoff
, lpages
, pages
);
262 goto out
; /* leave if some pages were missing */
264 /* check the pages for physical adjacency */
268 for (loop
= lpages
; loop
> 1; loop
--)
269 if (*ptr
++ != page
++)
272 /* okay - all conditions fulfilled */
273 ret
= (unsigned long) page_address(pages
[0]);
278 for (loop
= lpages
; loop
> 0; loop
--)
286 /*****************************************************************************/
288 * set up a mapping for shared memory segments
290 int ramfs_nommu_mmap(struct file
*file
, struct vm_area_struct
*vma
)
292 return vma
->vm_flags
& VM_SHARED
? 0 : -ENOSYS
;